Complete and interpret two-way frequency tables
Use two classifications together, recover missing interior counts from consistent margins, and distinguish intersections from totals.
Exam scope and assessment notes
The first six lessons are shared Foundation work inherited by Higher; the last four are additional Higher histograms and cumulative-frequency work. Construct actual labelled diagrams with their scales, units and keys. Unequal continuous intervals need frequency density and area; partial-class and straight-guide readings are estimates, and a flat inverse can be an interval. Numerical agreement does not award marks or establish mastery; written explanations need human review. Statistical measures and probability remain separate. Linear November 2026/June 2027 entries and regional-centre eligibility differ from modular awards. Publisher map/contents are navigation only: F6.1Aii is a modular subpart, not the whole linear F6.1A row. Book1 Handling Data3 map398–428 differs from proof397/summary426/next428; Book2 Handling Data6 map208–222 differs from proof207/summary221/next222. Relevant chapter and Hub bodies remain unavailable; specialist and formal-assessment approval remain pending.
Before you begin
- Add and subtract nonnegative whole-number counts.
- Follow labelled rows and columns.
- Distinguish the same population classified twice from two separate samples.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does an interior cell at row R and column S count?
What you will learn
- Label both classifications and interpret each interior intersection.
- Recover missing counts from row and column totals and cross-check the grand total.
- Compare stated margins without double counting individuals.
Draw the supplied two-way table with row categories Robotics, Drama and column categories bus, walk. The interior entries are Robotics: bus 18, walk 12; Drama: bus 9, walk 21. All margins are blank. Complete every blank cell and margin. State the Robotics–walk intersection count and compare the bus and walk column totals by first minus second. Explain why margins are not extra individuals.
Choose your representation, enter its actual categories, counts, geometry and labels, and explicitly record it. No table margin, scale, missing sector, density, cumulative point or reading trace is filled for you.
Original supplied data
Only literal data are supplied. A missing entry is displayed as not supplied; requested totals, frequencies, angles, density calibration, cumulative constructions and read-off traces are not generated on this board.
All metric panels in this board share one camera and equal Cartesian drawing units. Equal full widths, heights and pie radii therefore stay visibly comparable; no individual panel is independently fitted. Histogram numerical frequency density is its entered vertical calibration. Tables and tally strokes are symbolic displays.
No requested target representation has been supplied or recorded. Construct your own actual table, icons, bars, sectors, cumulative guide or reading trace.
Blue is supplied geometry, amber is my actual work, purple is dirty retained work and green is a separately gated reference. Rendering never repairs a wrong count, overlap, radius, calibration, cumulative decrease or read-off elbow. Tool coordinates are bounded to±1000000; finite unsupported portions are not silently clamped. Up to1000 explicit pictogram pieces and100 tally bundles per displayed row are rendered. Screen size is not physical instrument calibration. Readiness and fixed numerical comparison do not mark reasoning, award marks, prove mastery or provide teacher/specialist/formal-assessment approval.
Observed and whole-class counts stay distinct from within-class histogram or cumulative-guide estimates. A zero-frequency plateau can give an interval of inverse readings. No median, quartile, midpoint-mean or probability teaching credit is supplied by this display.
My complete two-way table and margins
No actual representation is recorded for this action.
The board places only the coordinates you explicitly choose into the selected slot. It generates no other corner, bar, sector or reading elbow. Interval-area bounds are two measurements, not a planar point.
My quantities, conclusions and explanation
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Explain the actual construction and its conditions. Text presence does not establish a correct argument.
These original fixed cases support self-checking. They do not mark proofs or written explanations, award marks or mastery, certify instrument accuracy, or provide specialist or formal assessment approval. Within-class histogram and cumulative-guide readings are estimates, while supplied whole-class counts remain exact. A plateau may give an interval rather than one inverse reading.
Read both labels at an intersection
A two-way table classifies the same individuals in two ways. A row might describe one characteristic and a column another. An interior cell counts those satisfying both its row label and its column label. Read those two labels together before quoting a number; a row total answers a different question from an individual cell.
The row categories must separate the individuals without overlap, and the column categories must do the same. Under that arrangement each person contributes to one interior cell. The margins summarise those cells: a person appears in a row total and a column total because these are summaries, not extra people added to the sample.
Use totals as equations
To find one missing entry in a row, subtract all its known entries from the row total. A missing column entry can be found in the same way. When several entries are absent, start with a row or column containing exactly one unknown, fill that cell, then use the newly completed information to continue.
Check every completed row against its total and every completed column against its total. Both sets of margins should add to the same grand total. A negative recovered count or contradictory margins cannot be repaired by choosing a convenient positive value. If the supplied equations leave several possible tables, the missing data are not determined uniquely.
Compare counts with their meanings intact
An interior count is an intersection; a margin combines several intersections. When asked for first-column minus second-column total, use that stated order, so a negative difference means the first is smaller. Include the category names when explaining a comparison instead of reporting a signed number without its meaning.
Do not add all interior cells and all margins together to count the sample: that repeats the same individuals. Display the full labelled table, including a clearly distinguished totals row and totals column, so the reader can see how the summaries were obtained. These are count and representation tasks; a table alone is not a completed conditional-probability argument.
Sources for this lesson
- Pearson Mathematics A linear specification · Issue 2 · Foundation printed 24 / physical 30; Higher printed 39 / physical 45; inheritance printed 27 / physical 33
- Pearson 2026/2027 entry manual · centre regions physical 3; Mathematics A physical 25
- Pearson second-edition modular book/Hub map · literal navigation only · physical 7, 9, 11
Pause and explain
A row total is 37. Its known entries are 8 and 14, with one cell blank. What completes the row?
Worked example
Draw the supplied two-way table with row categories Robotics, Drama and column categories bus, walk. The interior entries are Robotics: bus 18, walk 12; Drama: bus 9, walk 21. All margins are blank. Complete every blank cell and margin. State the Robotics–walk intersection count and compare the bus and walk column totals by first minus second. Explain why margins are not extra individuals.
Show the worked solution
- A row total combines all its column categories. Add across each row: Robotics: 18+12=30; Drama: 9+21=30.
- The completed interior is Robotics: bus 18, walk 12; Drama: bus 9, walk 21. Row totals are 30, 30 and column totals are 27, 33; both sets add to the grand total 60.
- The first-row/last-column intersection is Robotics–walk=12. The stated column difference is 27−33=-6; bus has 6 fewer.
- Write a clearly labelled totals row and column and verify each completed sum. Every individual belongs to one interior cell; the row, column and grand totals summarise those same people, so adding margins again would double count.
Answer Completed interior: Robotics: bus 18, walk 12; Drama: bus 9, walk 21. Row totals 30, 30; column totals 27, 33; grand total 60. The requested intersection is 12, and bus minus walk is -6. Margins repeat summaries of the same individuals, not additional people.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →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.
Draw the supplied two-way table with row categories East, West and column categories cycle, bus, walk. The interior entries are East: cycle 11, bus 14, walk blank; West: cycle 9, bus blank, walk 13. Supplied row totals are 30, 30, column totals 20, 22, 18, and grand total 60. Complete every blank cell and margin. State the East–walk intersection count and compare the cycle and bus column totals by first minus second. Explain why margins are not extra individuals.
Give me a hint
Begin with a row or column containing only one blank. Then use the other margins to check it.
Compare my reasoning
- Use the supplied row or column total with one missing interior count. East–walk=30−(11+14)=5; West–bus=30−(9+13)=8.
- The completed interior is East: cycle 11, bus 14, walk 5; West: cycle 9, bus 8, walk 13. Row totals are 30, 30 and column totals are 20, 22, 18; both sets add to the grand total 60.
- The first-row/last-column intersection is East–walk=5. The stated column difference is 20−22=-2; cycle has 2 fewer.
- Write a clearly labelled totals row and column and verify each completed sum. Every individual belongs to one interior cell; the row, column and grand totals summarise those same people, so adding margins again would double count.
Completed interior: East: cycle 11, bus 14, walk 5; West: cycle 9, bus 8, walk 13. Row totals 30, 30; column totals 20, 22, 18; grand total 60. The requested intersection is 5, and cycle minus bus is -2. Margins repeat summaries of the same individuals, not additional people.
Look for these in your work
- Complete the labelled interior and every total without negative or contradictory counts.
- Read the requested intersection and keep the stated order of subtraction.
- Explain one-cell membership and avoid adding margins to the sample again.
Draw the supplied two-way table with row categories Year7, Year8, Year9 and column categories mealA, mealB. The interior entries are Year7: mealA 16, mealB blank; Year8: mealA 19, mealB 11; Year9: mealA blank, mealB 18. Supplied row totals are 30, 30, 30, column totals 47, 43, and grand total 90. Complete every blank cell and margin. State the Year7–mealB intersection count and compare the mealA and mealB column totals by first minus second. Explain why margins are not extra individuals.
Give me a hint
Begin with a row or column containing only one blank. Then use the other margins to check it.
Compare my reasoning
- Use the supplied row or column total with one missing interior count. Year7–mealB=30−(16)=14; Year9–mealA=30−(18)=12.
- The completed interior is Year7: mealA 16, mealB 14; Year8: mealA 19, mealB 11; Year9: mealA 12, mealB 18. Row totals are 30, 30, 30 and column totals are 47, 43; both sets add to the grand total 90.
- The first-row/last-column intersection is Year7–mealB=14. The stated column difference is 47−43=4; mealA has 4 more.
- Write a clearly labelled totals row and column and verify each completed sum. Every individual belongs to one interior cell; the row, column and grand totals summarise those same people, so adding margins again would double count.
Completed interior: Year7: mealA 16, mealB 14; Year8: mealA 19, mealB 11; Year9: mealA 12, mealB 18. Row totals 30, 30, 30; column totals 47, 43; grand total 90. The requested intersection is 14, and mealA minus mealB is 4. Margins repeat summaries of the same individuals, not additional people.
Look for these in your work
- Complete the labelled interior and every total without negative or contradictory counts.
- Read the requested intersection and keep the stated order of subtraction.
- Explain one-cell membership and avoid adding margins to the sample again.
Draw the supplied two-way table with row categories Morning, Afternoon and column categories repair, replace. The interior entries are Morning: repair 24, replace blank; Afternoon: repair blank, replace 22. Supplied row totals are 40, 40, column totals 42, 38, and grand total 80. Complete every blank cell and margin. State the Morning–replace intersection count and compare the repair and replace column totals by first minus second. Explain why margins are not extra individuals.
Give me a hint
Begin with a row or column containing only one blank. Then use the other margins to check it.
Compare my reasoning
- Use the supplied row or column total with one missing interior count. Morning–replace=40−(24)=16; Afternoon–repair=40−(22)=18.
- The completed interior is Morning: repair 24, replace 16; Afternoon: repair 18, replace 22. Row totals are 40, 40 and column totals are 42, 38; both sets add to the grand total 80.
- The first-row/last-column intersection is Morning–replace=16. The stated column difference is 42−38=4; repair has 4 more.
- Write a clearly labelled totals row and column and verify each completed sum. Every individual belongs to one interior cell; the row, column and grand totals summarise those same people, so adding margins again would double count.
Completed interior: Morning: repair 24, replace 16; Afternoon: repair 18, replace 22. Row totals 40, 40; column totals 42, 38; grand total 80. The requested intersection is 16, and repair minus replace is 4. Margins repeat summaries of the same individuals, not additional people.
Look for these in your work
- Complete the labelled interior and every total without negative or contradictory counts.
- Read the requested intersection and keep the stated order of subtraction.
- Explain one-cell membership and avoid adding margins to the sample again.
Common mistakes
- Using a row total when the question asks for one row-and-column intersection.
- Adding margins to the interior cells as though they were extra individuals.
- Accepting negative missing counts or inconsistent totals without questioning the supplied data.
What can you explain now?
The row totals add to 72, but the column totals add to 71 for the same complete sample. Is a unique completed table justified?
Compare with the explanation
No. The margins are inconsistent and must be checked against the source data.
Both sets of margins count the same individuals once, so their grand totals must agree before a valid completed table can be accepted.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain how a cell, row total, column total and grand total differ, then describe a safe order for recovering several missing cells.
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.