IGCSE · Pearson Edexcel · 4MA1

Higher: applying probability models to simple problems

Translate simple contexts into probability trees, recover admissible integer contents and combine conditional branches with interpreted predictions.

Pearson4MA1 · Probability · Additional Higher 6.3A / Additional Higher 6.3B / Additional Higher 6.3C / Additional Higher 6.3D

Exam scope and assessment notes

The first five lessons are shared Foundation work inherited by Higher; the final four are additional Higher trees, simple conditioning and applications. State the actual random mechanism, equally likely elementary outcomes, complete sample spaces and event membership. Distinguish independence from replacement and mutual exclusivity, observed relative frequency from theoretical probability, and expected frequency from a guaranteed count. Retain every ordered without-replacement history and its remaining contents. Conditional probabilities use the conditioning population; an empty condition is undefined. Inverse object counts are nonnegative integers in the original positive-denominator model. Written reasoning and assumptions still need human review; no marks or mastery are awarded. Specialist and formal-assessment approval remain pending. This is Issue2 linear4MA1; November2026/June2027 and regional-centre eligibility differ from modular awards. Literal Book1 HandlingData1/2/3 and Hub tags are navigation only; no Book2 tag or probability chapter/Hub body is verified. Keep map228–242/proof229–243/next244, map303/proof304–328/next329 and map398–428/proof397/summary426/next428 separate. Missing explicit Hub tags A/B/F/J stay missing. The common elementary two-coin model is not claimed as a novel model. Statistical-measures and diagram prerequisites do not themselves establish probability coverage.

Before you begin

PR6–PR8
shared expected frequency
simple equations/quadratic factorisation and positive counts

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

An equation for an unknown number of tokens has an algebraic negative root. What should happen next?

What you will learn

Translate a simple context into labelled tree paths or finite conditional counts, keeping every model assumption.
Use a given event probability to recover an unknown integer content, rejecting nonphysical algebraic roots.
Combine disjoint conditional branches and use expected frequency as an interpreted count; no formal statistical test, independence inference from mere appearance or unsupported expected-profit theorem.

A bag contains x red and 4 blue tokens. Two uniform draws are made with replacement and independent remixing. P(two blue)=4/25. Find x and P(two red), explaining which square-root sign is physically allowed. Draw the model tree with x first, then label the recovered probabilities. Use the nonnegative integer domain for the unknown count and keep the original total positive.

Enter the original physical identities, ordered outcomes, selected populations, weights, observed counts and actual geometry yourself. No space, history, support, denominator, rate, count, unknown proposal or probability is filled. A recorded representation is an attempt, not a correctness result.

My current representation

Original givens and my literal probability work

Original supplied information

knownBlue

unknownColour

red

unknownCountDomain

nonnegative integer

draws

replacement

true

independentRemixedDraws

true

P_twoBlue

4/25

The original physical labels, given weights and stated mechanism are supplied. No completed sample space, tree, event selection, total, relative frequency, expected count, unknown count or requested probability is filled. Counts determine masses; drawn circle areas and tree lengths do not.

Whole view turn °

Every planar panel shares this uniform camera. Experiment rate positions are categorical layout positions, not a fabricated cumulative trial history. The prediction panel labels its separate trials/expected-events units. Pan, zoom and turn affect the view only.

Empty own drawing plane; no probability representation is supplied

Blue supplied diagrams are schematic; amber records are actual learner work; purple is dirty retained work; dashed work is unready. Native clipping does not clamp, snap or repair points. Exact keyboard tokens and numeric-only free inverse coordinates are separate: a finite inverse click remains actual raw work even when exact-token bounds later reject it. The finite tool uses coordinates±1,000,000, up to40 tree nodes/81 terminals/4 branches,100 grid cells or weights. These are tool limits. No numerical agreement, written-text presence, drawn tree, sample space or reference proves reasoning, grants marks/mastery, or supplies teacher/specialist/formal-assessment or book-body approval.

Construct my complete labelled probability tree

No actual representation is recorded.

The question’s event names are twoBlue; twoRed. Enter an event row and its actual favourable/conditioning populations yourself. The original replacement or independence mechanism remains the supplied question; the interface never generates remaining counts or conditional weights.

My actual complete treeMy unknown-count proposal statement

My actual nonterminal nodes

Up to 40 explicit entries. A new row begins blank.

My actual terminal paths

Up to 81 explicit entries. A new row begins blank.

My event selections

Up to 32 explicit entries. A new row begins blank.

Choose an explicit my unknown-count proposal statement.

No current explicit planar target is selected. Grid identities, event memberships, row indices, scalar weights and ordered histories use their own symbolic fields; none becomes a fake x/y coordinate.

My quantities, conclusions and explanation

red Count

Use the original physical integer-count domain; inadmissible roots remain explicit only where requested.

total

Use the original physical integer-count domain; inadmissible roots remain explicit only where requested.

single Blue

Keep the original event support, probability/conditioning assumptions and requested format. No denominator or answer is inserted.

single Red

Keep the original event support, probability/conditioning assumptions and requested format. No denominator or answer is inserted.

two Red

Keep the original event support, probability/conditioning assumptions and requested format. No denominator or answer is inserted.

Negative probability root to reject in your reasoning

Keep the original event support, probability/conditioning assumptions and requested format. No denominator or answer is inserted.

Algebraic count root candidate 1

Use the original physical integer-count domain; inadmissible roots remain explicit only where requested.

Algebraic count root candidate 2

Use the original physical integer-count domain; inadmissible roots remain explicit only where requested.

Explain your model, selected outcomes and calculation; address the stated limitation.

A nonblank explanation is an attempt for human review, not approval of reasoning.

These original finite cases are self-checks, not automatic marking, mastery, teacher/specialist/formal-assessment or unavailable book-body approval. Equally likely physical outcomes, independence, replacement and comparable experimental conditions must be justified from each original question. An empty conditioning population is undefined, not probability zero. Expected counts are model predictions, not guaranteed observations. No statistics or modular credit is inferred.

Translate the context before calculating

Choose the sequence of stages that reflects the original process: a source followed by an item condition, weather followed by attendance, or successive draws from a box. Label the outcomes and the probability of each branch conditional on its own preceding history. Original marginal probabilities cannot replace stated conditional probabilities merely because the labels are familiar.

Complete the tree and identify the terminal histories belonging to the requested event. Multiply factors along each history, then add disjoint relevant paths. Reversing a condition uses the appropriate event contribution divided by the whole conditioning-event probability. Give that denominator a clear meaning and check it is positive before division.

Recover an unknown with its physical domain

An unknown number of objects is a nonnegative integer, and the total must support the stated number of draws. Write the original event probability as an equation in that count. With independent replacement, repeated category probabilities can produce a square; without replacement, both the category count and total change along the second branch. Keep these models separate when forming the equation.

Solving the equation may produce algebraic values that are not possible contents. A negative square-root value cannot be a probability, and a negative object count cannot describe the box. Show the algebraic alternatives, apply the physical domain and substitute every retained candidate into the original probability expression. Rearrangement alone does not validate a root or remove denominator restrictions.

Interpret conditional applications honestly

A mixture probability is the sum of its disjoint source-and-event paths, each weighted by that source’s probability. When conditioning on the event, compare the relevant source contribution with the total event probability. This finite path calculation does not permit unweighted averaging of conditional probabilities when sources are selected with different weights.

An expected count multiplies the event probability by the number of comparable modelled trials and remains a prediction rather than a guarantee. If conditional event probabilities differ between possible earlier conditions, independence must not be assumed. State the selection mechanism, physical count restrictions and the limits of the model; a correct numerical self-check does not mark the written argument or validate an actual system.

Sources for this lesson

Pause and explain

An item comes from A with probability 1/4 and B with 3/4. Its event probabilities are 1/5 given A and 1/3 given B. What is the overall event probability?

Put the idea to work

Worked example

Show the worked solution

Draw the original stages and label given conditional probabilities or expressions involving the unknown count. Form the requested event equation or weighted path sum, keep the physical count domain, and check the original model after solving.
The positive single-blue probability is 4/(x+4). Independence with replacement gives [4/(x+4)]²=4/25.
A probability cannot equal −2/5, so 4/(x+4)=2/5. Thus x+4=10 and x = 6 red tokens.
The red probability is 6/10=3/5; P(two red)=(3/5)²=9/25. The recovered integer count satisfies the original model and nonnegative domain.
Begin with first-stage red x/(x+4),blue 4/(x+4), and repeat those fractions after each branch only under the stated independent replacement model. After solving, substitute x=6 and verify all four terminal probabilities sum to 1.

Answer The positive blue probability is 2/5, so total 10 and x=6 red. The negative probability root−2/5 is inadmissible. The recovered replacement tree has red 3/5,blue 2/5 at each split: RR 9/25,RB 6/25,BR 6/25,BB 4/25. P(two red)=9/25; the original two-blue probability checks as 4/25.

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Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.

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From guided practice to a new situation

Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.

1 · Guided

A random item comes from supplier A with probability 2/5 and B with probability 3/5. The faulty probabilities are 1/20 given A and 1/10 given B. Draw the two-level tree. Find P(faulty), P(B given faulty), and the expected faulty count among 500 comparable selections.

Give me a hint

Draw the original conditional stages, form the event equation or weighted path sum, apply the count/probability domain and check the original expression.

Compare my reasoning

Draw the original stages and label given conditional probabilities or expressions involving the unknown count. Form the requested event equation or weighted path sum, keep the physical count domain, and check the original model after solving.
The two faulty paths have probabilities 2/5×1/20=1/50 and 3/5×1/10=3/50. The supplier events are mutually exclusive.
Add these paths to get P(faulty)=4/50=2/25. Within the faulty event, the B path contributes 3 of those 4 parts, giving P(B | faulty)=3/4.
Expected faulty count in 500 is 500×2/25=40 under the same selection/quality model. This is a finite path-and-restricted-total calculation, not an invocation of an unlisted formal theorem.
Complete the nonfaulty branches too: P(not faulty given A)=19/20 and given B=9/10. The four terminal products are A/faulty 1/50,A/not-faulty 19/50,B/faulty 3/50,B/not-faulty 27/50, summing to 1.

Faulty path contributions are 1/50 from A and 3/50 from B, so P(faulty)=2/25. P(B given faulty)=(3/50)/(2/25)=3/4. Expected faulty count in 500 comparable selections is 40, not a guaranteed realised number.

Look for these in your work

Label source and conditional outcome levels correctly.
Sum disjoint faulty paths.
Condition on the total faulty event and interpret expected frequency.

2 · Independent

A bag contains n red and 5 blue tokens. Two uniform draws are made without replacement and P(two blue)=2/9. Form an equation, find all algebraic roots and select the physical value of n. Draw the corresponding conditional tree and check the event probability.

Give me a hint

Draw the original conditional stages, form the event equation or weighted path sum, apply the count/probability domain and check the original expression.

Compare my reasoning

Draw the original stages and label given conditional probabilities or expressions involving the unknown count. Form the requested event equation or weighted path sum, keep the physical count domain, and check the original model after solving.
The event has probability 5/(n+5)×4/(n+4)=2/9. Rearranging gives (n+5)(n+4)=90.
Expanding and factoring yields n²+9 n−70=(n−5)(n+14)=0, so the algebraic roots are 5 and −14.
Only n = 5 is a nonnegative count. With ten tokens, the original event is 5/10×4/9=2/9, confirming the value.
On the nonnegative integer count domain, n+5 and n+4 are positive. After the valid root n=5, first red/blue are each 5/10; after red the split is 4/9,5/9 and after blue it is 5/9,4/9. This produces the four checked path products.

The equation is 5/(n+5)×4/(n+4)=2/9, equivalent on the count domain to(n+5)(n+4)=90. It gives n²+9 n−70=(n−5)(n+14)=0, so roots 5 and−14. Reject−14 as a count; n=5 gives total 10 and original probability 5/10×4/9=2/9. The recovered tree has RR 2/9,RB 5/18,BR 5/18,BB 2/9.

Look for these in your work

Reduce the second total and blue count.
Preserve both algebraic roots before applying context.
Check the valid integer count in the original probability.

3 · Transfer

A simple daily model gives dry weather probability 3/4 and wet probability 1/4. A person attends with probability 2/3 given dry and 2/5 given wet. Draw the weather/attendance tree. Find P(attends), P(wet given attends), and the expected attendance count across 600 comparable modelled days. State why independence of weather and attendance must not be assumed.

Give me a hint

Draw the original conditional stages, form the event equation or weighted path sum, apply the count/probability domain and check the original expression.

Compare my reasoning

Draw the original stages and label given conditional probabilities or expressions involving the unknown count. Form the requested event equation or weighted path sum, keep the physical count domain, and check the original model after solving.
The attendance paths are 3/4×2/3=1/2 for dry and 1/4×2/5=1/10 for wet. Add them to obtain 3/5.
Within all attendance paths, the wet part is (1/10)/(3/5)=1/6. Expected attendance count is 600×3/5=360.
Attendance has different stated probabilities after dry and wet weather, so it is not independent of weather in this model. The expected count is not a guaranteed real sequence of days.
Complete both outcomes after each weather branch: attend/not-attend are 2/3,1/3 after dry and 2/5,3/5 after wet. The four terminal products are 1/2,1/4,1/10,3/20 and sum to 1; reverse conditioning uses only the two attendance paths.

Dry-and-attends contributes 1/2; wet-and-attends 1/10. P(attends)=3/5, P(wet given attends)=1/6 and expected attendance across 600 comparable modelled days is 360. Attendance is not independent of weather because the stated conditional attendance probabilities differ.

Look for these in your work

Use the supplied conditional probabilities.
Condition on attendance when reversing the question.
Explain model dependence and prediction limits.

Common mistakes

Averaging source-conditional probabilities without their source weights.
Accepting an algebraic root that is a negative count or probability.
Replacing a conditional model by an unsupported independent product or a guaranteed future count.

Recall without your notes

What can you explain now?

Why must an admissible recovered count be substituted into the original probability model?

Compare with the explanation

It checks the original denominators, sampling rule and event probability after the physical-domain filter.

Algebraic manipulation can introduce inadmissible alternatives or obscure a denominator restriction; the original event provides the final check.

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Make it stick

Explain the event model, all needed path factors, any rejected algebraic value and the meaning and limits of a predicted count.

If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.

Keep learning Mathematics A

Check the official syllabus Issue 2 · November 2026 / June 2027 entries checked

Course scope and assessment

Linked teaching: sections 1.1 to 1.11, 2.1 to 2.8, 3.1 to 3.4,4.1–4.11 and5.1–5.2 and6.1–6.3; 2.5, 3.2,3.4 and5.1 are Higher only. This includes Foundation content inherited by Higher and Higher extensions for recurring decimals, surds, fractional powers, algebraic sets, Venn counts, repeated percentage changes, calculations with measurement bounds and standard-form application problems. Algebra includes Foundation symbols, integer index laws, substitution, like terms, brackets and monic factorisation, plus Higher fractional indices, multiple brackets, non-monic factorisation, algebraic fraction operations with domain restrictions, completing the square and proofs. Formulae include derivation from words and diagrams, substitution, single-occurrence subject changes including squares and roots, and Higher repeated-subject and harder power/root rearrangements. Linear equations cover both sides, brackets, fractional coefficients and constructing models from data. Section 2.5 adds all eight direct/inverse x, square, cube and square-root proportion families with actual graph exploration and domain checks. Section 2.6 adds shared elimination and substitution, exact fractions, contextual feasibility and repeated or inconsistent conditions; the additional Higher graphical lesson interprets genuine-line intersections, vertical lines and off-screen crossings. Section 2.7 adds Foundation monic quadratic factorisation, with Higher general factorisation, quadratic-formula and completing-square alternatives, context derivation and line–parabola/line–circle systems including full branches and exact paired solutions. Section 2.8 adds required open/closed number-line intervals, linear and compound solving, construction and identification of Cartesian regions, and Higher quadratic sign intervals and harder linear regions. Its Cartesian boundary-drawing convention note does not remove number-line endpoint requirements. Section 3.1 adds term-to-term and position-to-term generation, integer continuation and linear nth terms, plus Higher arithmetic a,d recovery, the general nth-term formula and finite arithmetic sums. Section 3.2 adds Higher-only mappings, both function notations, actual domain/range reasoning, composition in Pearson order with original restrictions, and affine/rational/restricted-branch inverses. Section 3.3 has nine shared coordinate, straight-line, travel, speed, conversion and quadratic-plotting lessons, followed by two additional Higher line-equation lessons, four Higher graph-family lessons, nine transformation/equation-recovery lessons and three drawn-tangent/intersection lessons. All nine Foundation source rows have lesson links, with paired interpretation and linear/quadratic plotting breadth guards. The broad additional Higher H3.3A row requires integer polynomial/cubic, sparse mixed reciprocal, degree sine/cosine and degree tangent lessons with every practice stage. H3.3B requires all four transformation forms across linear, quadratic, degree sine and degree cosine functions in eight core lessons; H3.3C also requires their algebra recovery and the ninth domain/equivalence/order synthesis lesson. H3.3D requires drawn-tangent construction and signed rise/run using actual units; calculus is not a replacement. H3.3E requires both line/quadratic and genuine line/cubic intersections and their nonlinear-minus-linear difference graphs, with all practice stages. All sixteen Graphs source rows now have teaching and staged-practice links; exhaustive subskill approval, mastery and assessment readiness remain unestablished. Section 3.4 adds six Higher-only lessons for variable rates, integer-power differentiation, gradient/rate conditions, stationary coordinates classified by original graph shape, one-dimensional motion and other practical models. H3.4C requires gradient and stationary slices; H3.4E requires both motion and other-practical slices. Preserve original domains, negative-power exclusions, admissible counts and boundary candidates. All five source rows have structural links, not exhaustive subskill approval or specialist/assessment validation. Section4.1 adds six shared Foundation/inherited-Higher lessons for selected acute/right/obtuse/reflex arcs, point/straight/intersection and parallel-transversal angles, triangle sums/exteriors, isosceles/equilateral and right/mixed triangles. All four shared rows have structural links; B requires both local and parallel strands and D both special and right-triangle strands, each with every practice stage. No additional H4.1 rows are invented. Preserve labelled geometry and reasons, the auxiliary-parallel triangle-sum argument, actual straight extensions, inclusive equilateral/isosceles and right-isosceles categories, and impossible/insufficient-data checks. Section4.5 constructions,4.4 measurement/bearings and the full H4.7 reasoning scope remain separate, without a blanket formal-proof waiver. Section4.2 adds seven shared Foundation/inherited-Higher Polygons lessons for all nine named polygon examples, convex/concave quadrilateral sums, all six named quadrilateral property families, general/regular polygon angles and congruence correspondence. Its seven rows A–G have structural links, with no additional Higher rows; C requires both family lessons and every practice stage. F/G remain two distinct published IDs supported by the same congruence lesson. Rhombus/square and kite endpoint-angle bisection and isosceles-trapezium equal diagonals are conservative standard-property breadth, not invented verbatim source bullets. Preserve reflex interiors, valid internal triangulations, local trapezium/kite conventions, exact integer side counts and impossible-data guards. Section4.3 symmetry,4.5 formal constructions,4.11 similarity and the full H4.7A reasoning programme remain separate. Literal book tags omit A; G has no Hub tag, and the Book2 map/proof congruence location and chapter7 page-range conflict remain unresolved. Section4.3 adds three shared Foundation/inherited-Higher Symmetry lessons for the one F4.3A source row, requiring every lesson and practice stage for the joint line/rotation capabilities. Draw all mirror lines, test a fixed original against a separate tracing about a chosen centre, count identity once and distinguish order1 from a blank circle’s non-finite rotations. Preserve indentations and true physical disk/colour features; the chosen missing-vertex parallelogram completion is original breadth, not an extra row or4.5construction credit. No additional H4.3 row is invented. The sole literal book link is Book2 Shape and Space6; no Book1 tag or explicit4.3Hub tag is invented, and its mapped chapter body/full final-book alignment remains unverified. Section4.5construction,5.2transformations,4.11similarity and full Higher reasoning remain separate. Section4.4 adds eight shared Foundation/inherited-Higher Measures lessons for seven A–G source rows and no additional Higher rows. Use complete instrument-scale, time-interval, sensible-estimate, nearest-degree protractor and three-figure-bearing teaching. F4.4F requires the full speed lesson; broad F4.4G requires speed, density and pressure, each with its worked explanation and every practice stage, with source binding on the same complete record. Preserve calibrated ticks and actual instrument action, compatible units, midnight/day order, approximate readings and north conventions. Keep numerical references hidden until calibrated attempts. Time recovery requires positive speed; at zero speed positive distance is impossible and zero distance alone is underdetermined. Density uses positive volume, displacement differences and explicit additive-volume assumptions; pressure uses the given formula, supplied forces and positive contact areas. Literal book navigation names only D and G; no A/B/C/E/F tags are invented, and Book1 map255–268/proof256–269 remains unresolved. These structural links do not complete4.5 instrument/compass constructions or scale drawings,5.2 transformations or formal assessment. Section4.5 adds six shared Foundation/inherited-Higher Construction lessons for four A–D rows and no additional Higher rows. A requires both nearest-millimetre measurement and actual line drawing. BroadB requires complete triangles and other two-dimensional shapes; broadD requires both straight-edge-and-compasses bisectors. Source binding and complete teaching/worked/all three practice stages must belong to the same required record. Use real ruler, protractor and compass action with retained construction evidence, physical calibration and honest approximate readings. Keep private endpoint readings, pose coordinates, solved vertices/crossings and reference directions hidden before instrument attempts. Respect valid mirror branches and selected minor/reflex angles; reject impossible triangles, insufficient data and degenerate crossings. Scale drawings require construction before measuring the unknown, compatible units and a labelled positive scale; drawing placement offsets remain givens. Literal book navigation names B/C/D only in Book2 Shape and Space6 with Hubs37/36/38. A has no literal chapter/Hub tag and no Book1 tag is invented. Public proof contents agree with map128–160 and show generic Constructions139, but the relevant body, full-book/Hub content and exact subtype pages remain unavailable. These structural links do not grant4.6 circle properties,4.7 whole geometrical reasoning,4.8 trigonometry,4.9 mensuration,4.11 maps/similarity,5.2 transformations or loci credit. The nearby circle formal-proof note is not imported. Section4.6 adds nine original Circle properties lessons for two shared Foundation and three additional Higher rows. The first three shared lessons cover all nine named parts, both chord/centre implications and both tangent facts. F4.6B requires both chord and tangent lessons. Additional Higher H4.6A requires both internal-chord and external-secant products with original named lengths, positive lengths and correct internal/near-far point order. H4.6B requires actual concyclic boundary vertices. H4.6C requires all five theorem parts across centre/circumference, diameter/same-segment, cyclic-opposite-angle and alternate-segment lessons. Every required slice needs substantive teaching, explained worked work and all three practice stages on one source-bound record; no half-row or untagged duplicate closes the bundle. Keep given marks separate from derived marks and retain selected major/minor arcs, tangent rays and physical algebraic-root domains. The no-formal-proof note belongs to H4.6C, not a blanket H4.6A/H4.7 exemption. Literal Book2 chapter5 tags F4.6B/H4.6B/H4.6C and chapter8 tags H4.6A/H4.6C are navigation only; no F4.6A or Book1 tag is invented. Chapter8 map326–349 versus proof chapter-start325 and next chapter349 remains unresolved; relevant final bodies and Hub content are unverified. These structural links do not complete construction, whole geometrical reasoning, trigonometry or mensuration, or establish specialist approval, mastery or formal assessment. Section4.7 adds five original Geometrical reasoning lessons for one shared F4.7A and one additional H4.7A row. The shared row jointly requires line/triangle, polygon and chord/tangent numerical reasoning, including lengths; the Higher row jointly requires both circle and mixed-angle standard-statement chains. Every required record needs substantive teaching, its explained worked example and all three fresh practice stages, with the source ID on that same complete record. Preserve actual diagram hypotheses, common arcs, contact radii, selected tangent rays, cyclic/straight point order, valid internal triangulations and the unknown regular-polygon outline after deduction. Each geometric equation needs a named reason; a correct number or sufficient text length does not validate an arbitrary written argument. The H4.6C formal-theorem-proof note remains local, not a blanket4.7 waiver. Only literal H4.7A Book1 Shape and Space1/Hub89,137,138,139 navigation is used; no Foundation4.7A or Book2 tag is invented. Public Book1 chapter60–99 is available but does not establish full Higher circle-angle or Hub body scope. These links do not award4.5construction skill, specialist approval, mastery or formal assessment. Section4.8 adds eleven original Trigonometry and Pythagoras’ theorem lessons for three shared F4.8A–C and six additional H4.8A–F rows. The first four are shared; the last seven are additional Higher. F4.8B jointly requires lengths with all acute ratios and inverse-angle work; H4.8C jointly requires sine-rule and cosine-rule teaching. Every row needs all its named source-bound records, substantive teaching, explained worked work and every Guided/Independent/Transfer stage. Preserve both missing-leg and missing-hypotenuse Pythagoras, signed bearing components with local north, all three obtuse functions, actual elevation/depression horizontals, admissible SSA branches and included-angle area restrictions. Three-dimensional work requires perpendicular sections and the actual foot/projection for a line-plane angle; plane-plane angles are excluded. Positive physical lengths, inverse domains, triangle inequalities, degree mode, exact forms and final-only rounding remain explicit. Chosen SSA two/one/no and inverse-area comparisons are safeguards, not extra syllabus rows. Literal navigation uses Book1 SS1–4 only: no Book2 tag or dedicated H4.8A Hub is invented. Hub145 is tagged F4.8A in SS1 and H4.8D in SS3; the former title does not extend Foundation into3D. Public Pythagoras body74–76 is available, but SS2/3/4 bodies and Hub content are unverified. SS2 map176–197 versus summary198, and SS3 map243–254 versus proof-start244/summary255 remain unresolved. No4.5construction,4.9mensuration, full-book, specialist, mastery or formal-assessment credit follows from these structural links. Section4.9 adds eight original Mensuration lessons for five shared F4.9A–E and one additional H4.9A row. The first six are shared; the last two are Higher. F4.9E jointly requires complete circle and semicircle/compound-boundary lessons; H4.9A jointly requires degree arcs/perimeters and sector-area/recovery lessons. Every required source-bound record needs substantive teaching, its explained worked example, checks and all Guided/Independent/Transfer stages. Retain both-direction linear/area conversions, exposed polygon boundary traces and internal joins, triangle/rectangle decomposition and contained disjoint cutouts, outside perpendicular heights, both parallelogram/trapezium methods, radius/diameter recovery and semicircle arc-versus-perimeter distinctions. Preserve major/remaining sector sweeps, positive physical roots, inverse dimensions, annular inner arcs and radial gaps, compatible square/linear units and question-specific precision; no universal3sf rule is invented. Radians are excluded; ordinary sector arc-plus-two-radii boundaries require0<θ<360, while a full disk has no radial cuts. Literal Book1 SS1 tags B/C/D/E and HigherA with Hubs47/48/118, plus Number4A/Hub14, are navigation only; no Book2 tag or verified Hub body is inferred. Public SS1contents summary98 versus actual99 and Number4map198–206 versus proof199–207/next208 stay explicit. Chosen compound/inverse/annular safeguards do not add source rows or grant construction, volume, similarity, full-book, specialist, mastery or formal-assessment credit. Section4.10 adds nine original 3D shapes and volume lessons for six shared F4.10A–F rows and one additional H4.10A row. The first seven are shared; the final sphere and right-cone lessons are additional Higher. Teach all seven named solid families, complete face/edge/vertex incidence with hidden features, planar triangle/rectangle surface inventories and cylinder surfaces with actual open/closed conditions. F4.10E requires both complete prism and cylinder-volume slices; H4.10A requires both complete sphere and right-cone surface-and-volume slices. Every required source-bound record needs substantive teaching, worked methods, checks and all Guided/Independent/Transfer stages. Preserve actual face altitudes, positive inverse dimensions, full-length groove conditions, internal capacity and fill levels, contact-patch removal, cubic unit factors and1L=1000cm³. Curved-solid tasks state their flat-face/rim/apex convention without inventing a universal mark-scheme count. Nets, joins, inverse applications and solid hemispheres are chosen breadth, not extra official rows or instrument, frustum, similarity, pyramid-volume or hollow-capacity credit. Keep exact values/π and question-specific precision, including explicit significant trailing zeroes or scientific form. Literal Book2 Shape and Space9 tags C/D/E/F and HigherA are navigation only; no A/B or Book1 tags are inferred. Hubs56/57/55/84/131 do not establish body coverage, and no F4.10F Hub tag is invented. Map359–385 versus proof358–384/next385 remains unresolved; relevant chapter body and full-book/Hub content are unavailable. Specialist, formal-assessment and mastery approval remain pending. Section4.11 adds seven original Similarity lessons for exactly two shared F4.11A/B rows and three additional H4.11A/B/C rows. The first four are shared correspondence, forward/inverse lengths, maps and plans; the final three cover area factors, volume factors and mixed problems. F4.11A requires both complete correspondence and length slices, and F4.11B requires both map and plan slices, with source binding, substantive teaching, worked methods, checks and every explained Guided/Independent/Transfer stage in the same actual record. Retain matching angles and every corresponding side, concave reflex corners, positive factors, inverse recovery, parallel/shared-vertex hypotheses, whole/part order, compatible units, route versus direct distance, and uniform print-resizing scale recovery. Higher work distinguishes k, k² and k³, positive roots, similarity hypotheses, unit powers, actual closed-cuboid total surfaces, physical dimensions, exact money before rounding, and parallel-section cone subtraction as a chosen application. No extra official row, transformations, instrument calibration, formal construction or general frustum-formula credit is claimed. Literal Book2 Shape and Space6 F4.11B/Hub36, Shape and Space7 F4.11A/Hub85, and Shape and Space9 H4.11A/B/C with Hubs143/144 are navigation only, with no Book1 tag invented. Shape and Space6 map128–160/proof128/summary159/next161, Shape and Space7 map223–248/proof222/summary247/next248, and Shape and Space9 map359–385/proof358/summary384/next385 remain explicit. The actual proof places Similar shapes at147 under Shape and Space6 while the literal F4.11A map tag remains under Shape and Space7; this topic-location conflict is unresolved. Relevant chapter and Hub bodies are unavailable; no full-book, specialist, formal-assessment or mastery approval follows. Section5.1 adds nine original additional Higher Vectors lessons for exactly H5.1A–G and no shared Foundation rows. All required source-bound notation, scalar, arithmetic, magnitude, route, position/division, parallel/collinear, simple-proof and intersection strands need substantive original teaching, an explained worked example and exactly one complete Guided/Independent/Transfer task in the same record. Preserve directed endpoints, signed/scalar and zero-vector exceptions, exact fractions and radicals, final-only rounding, current own head-to-tail joins, one-origin positions, t=0/t=1 endpoints and external points without clamping. Geometric conclusions require actual nonzero, nonparallel, noncollinear or simple-boundary hypotheses; formal two-to-four-symbol planar identities do not assert an independent spatial basis. H5.1G requires genuine explained geometric proof, not numerical resemblance or unchecked text. The H4.6C local theorem-proof note is not a blanket vector-proof waiver. Literal Book2 Shape and Space10 H5.1A–G map427–450/proof426/summary449/next450 remains unresolved; Hub167 covers A/B/C/D/F,168 A/E and169 G. Navigation does not establish modular equivalence. No Book1 tag or unseen Vectors chapter/Hub body is invented: the public uncorrected2025proof exposes contents and Number8 body, not Vectors. November2026/June2027 linear entry and regional-centre limits remain separate. Full-book, specialist, mastery and formal-assessment approval remain pending. Section5.2 adds twelve original shared Transformation geometry lessons across exactly F5.2A–M and no additional Higher row. Full source-bound bundles require substantive teaching, explained worked and exactly one complete Guided/Independent/Transfer task in each record. Retain every labelled corner and corresponding trace, signed/general rotations, complete equivalent mirror lines, common translation columns, rigid distances/angles, positive and fractional factors, supplied/free centres and factor1 identity exceptions. General-degree written3dp is separate from unrounded geometry. Ordered compositions are chosen breadth rather than an extra source row; compare both orders, including commuting perpendicular reflections, and distinguish reverse order from the inverse. Source/book/year and proof/physical-construction limits remain explicit. Graphical representation6.1 adds ten original lessons: six shared Foundation tabulation/two-way/pictogram/bar/pie/interpretation slices and four additional Higher histogram construction/reading and cumulative construction/use slices. Each complete source-bound record and every practice stage are required; tables or diagram names alone do not establish actual construction. Keep scales/units/keys, zero categories, unequal continuous widths and density/area, hidden missing calibration and pie labels, uniform partial-class estimates, cumulative boundaries and nonunique flat inverses. No Statistical measures6.2 or Probability6.3 credit follows. Literal book/Hub metadata is navigation only: Book2 Handling Data4 F6.1Aii is a modular subpart; Book1 Handling Data3 map398 starts differently from proof397 and Book2 Handling Data6 map208 from proof207. Relevant chapter/Hub bodies remain unavailable. Statistical measures6.2 adds eight original lessons: four shared Foundation list/frequency averages, simple mean problems and grouped midpoint estimates/modal classes; four additional Higher spread, discrete quartiles, median and IQR from cumulative diagrams. Every source-bound record needs substantive teaching, its explained worked example and all three unique practice stages. Preserve repeated positions, weighted counts, observed zero-frequency extremes, compatible units, grouped estimation limits, the explicitly chosen median-of-halves convention, actual graph guides, each curve’s own total and nonunique plateau intervals. Literal Book2 Handling Data4/5/6 tags and Hubs are navigation metadata only; no Book1 tag, complete chapter body or Hub access is inferred. Handling Data6 map208–222 versus proof207/summary221/next222 stays explicit. Statistical measures alone does not replace Probability6.3 teaching. Probability6.3 adds nine original lessons for ten shared F6.3A–J and four additional H6.3A–D rows. The first five are shared language/scales/models, complete single/two-event sample spaces, Venn probabilities, experimental estimates/expected frequencies and complement/mutually-exclusive addition; the final four are Higher independent trees, actual without-replacement trees, simple conditioning and contextual inverse/mixed models. Each required source-bound strand needs substantive teaching, an explained worked example and exactly one complete Guided/Independent/Transfer task in the same actual record. F6.3C requires both model and sample-space slices; H6.3A requires independent, dependent and application trees; H6.3B requires independent and application slices; H6.3C requires without-replacement, simple-conditioning and application slices; H6.3D requires conditioning and application slices. Retain physical identities, nonuniform weights, original ordered histories, complete branches/terminal events, unchanged versus changing contents, restricted positive conditional denominators and undefined empty conditioning. Experimental variability and fractional expected counts are model predictions rather than guaranteed observations. Inverse physical counts keep original nonnegative integer/positive-total domains. Chosen three-set, three-stage and inverse safeguards do not add source rows or a named general conditional theorem. Literal Book1 HandlingData1/2/3 tags and Hubs are navigation only; no Book2 tag or unseen probability chapter/Hub body is invented. Preserve map228–242/proof229–243/next244, map303/proof304–328/next329 and map398–428/proof397/summary426/next428; missing explicit Hub A/B/F/J tags remain absent. The common two-coin elementary model is not claimed as novel. All39 source sections and242 requirements now have structural teaching/practice links; that is not exhaustive subskill, teacher, full-book, mastery, specialist or formal-assessment approval. The independent source inventory contains 162 Foundation requirements and 80 additional Higher requirements; some lettered requirements contain multiple skills. A lesson link alone does not verify every skill or examination readiness. Written practice is self-checked, not automatically marked. Specialist approval and cumulative assessment have not been established. This course follows the linked Issue 2 linear 4MA1 specification. The 2026/2027 entry manual lists F/H in November 2026 and June 2027; regional FR/HR entries are June 2027 only and depend on centre eligibility. Modular 4XMAF and 4XMAH coverage is separate.