Higher: construct cumulative-frequency diagrams
Build running totals, plot upper class boundaries with the correct initial zero point, and retain flat intervals without inventing raw positions.
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
- Read continuous class boundaries and frequency tables.
- Add running totals and recover differences.
- Plot ordered pairs on consistently calibrated axes.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
A complete sample has its first class 12 < x ≤ 18. What initial point belongs before the first cumulative endpoint?
What you will learn
- Find cumulative counts or recover class frequencies by consecutive differences.
- Plot the lower-support zero point and every upper-boundary running total on calibrated axes.
- Draw a nondecreasing guide and explain zero-frequency flat intervals and within-class uncertainty.
The complete continuous sample measures time. The consecutive class boundaries are 0, 10, 20, 35, 50 s, with frequencies 6, 14, 18, 12. Each class is lower < time ≤ upper. Construct the labelled cumulative-frequency table and actual diagram, including the correct initial zero point, every upper-boundary point and the final total. Use consistent numerical scales. Explain any zero-frequency interval and why class midpoints are not the required plotting positions. State whether you use a smooth nondecreasing guide or a declared straight-segment guide.
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.
Blank construction plane
unready actual work. No target values or construction points are supplied.
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 plotted upper-boundary cumulative points and declared guide
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.
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.
Accumulate counts without changing boundaries
A cumulative count at a boundary is the number of observations at or below that boundary for the stated lower-open, upper-closed classes. Add each class frequency to the previous running total. The cumulative total therefore never decreases, and its final value equals the complete sample size.
The horizontal coordinates for the class totals are the actual upper class boundaries, not class midpoints. Include the lower boundary of the complete supplied range with cumulative count zero, because the sample has no observations below that first class in these tasks. That starting coordinate can be positive or negative; it need not be the origin of the axes.
Construct a calibrated nondecreasing guide
Label the horizontal axis with the measured quantity and its unit, and the vertical axis Cumulative frequency. Use consistent numerical scales on both axes, retaining unequal horizontal gaps between unequal class boundaries. Plot every required boundary-count pair accurately before joining them. A neat curve through incorrectly placed midpoints does not represent the cumulative table.
Use a smooth nondecreasing guide through the plotted points, or clearly declare a straight-segment interpolation guide when using that representation. Do not introduce downward turns, overshoot the sample total or suggest a uniquely known distribution inside a class. The supplied endpoint counts are exact grouped facts; the shape between them is a guide for later estimates.
Read differences and flat intervals
If a cumulative table is supplied instead of class frequencies, subtract successive cumulative values to recover each class count. These differences must be nonnegative and add to the final total. A decrease would contradict a cumulative count for the same complete sample, so it requires checking rather than a negative class frequency.
A zero-frequency class creates a horizontal part of the guide between its two boundaries. Inverse reading at that plateau count can correspond to a whole interval of measurements, not a unique point. A single endpoint chosen from that interval is not a uniquely recovered threshold. Distinguish that nonuniqueness from a missing or poorly drawn curve.
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
Consecutive cumulative counts are 7, 19 and 19. What are the next two class frequencies?
Worked example
The complete continuous sample measures time. The consecutive class boundaries are 0, 10, 20, 35, 50 s, with frequencies 6, 14, 18, 12. Each class is lower < time ≤ upper. Construct the labelled cumulative-frequency table and actual diagram, including the correct initial zero point, every upper-boundary point and the final total. Use consistent numerical scales. Explain any zero-frequency interval and why class midpoints are not the required plotting positions. State whether you use a smooth nondecreasing guide or a declared straight-segment guide.
Show the worked solution
- Accumulate the class frequencies from zero: 0+6=6; 6+14=20; 20+18=38; 38+12=50. Each new total includes all observations up to that upper boundary.
- The cumulative table at boundaries 0, 10, 20, 35, 50 is 0, 6, 20, 38, 50. Plot (0,0), (10,6), (20,20), (35,38), (50,50). The initial point is (0,0), set by the actual lower class boundary; the final cumulative count is 50.
- Label the horizontal axis time (s) and the vertical axis Cumulative frequency. Preserve actual boundary spacings and plot at upper boundaries, because each running total counts observations up to that boundary. Join with a nondecreasing guide; a declared straight-segment guide is one reproducible choice.
- All class frequencies are positive, so every consecutive endpoint total increases. Check that the guide never decreases or overshoots the final total; a drawn route between endpoints is not exact knowledge of raw positions within a class.
Answer Class frequencies 6, 14, 18, 12; cumulative counts 0, 6, 20, 38, 50 at boundaries 0, 10, 20, 35, 50 s; total 50. Required plotted pairs: (0,0), (10,6), (20,20), (35,38), (50,50). Construct the actual labelled nondecreasing diagram on uniform numerical axes; do not plot class midpoints.
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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.
The complete continuous sample measures mass. The consecutive class boundaries are 100, 120, 150, 190, 250 g, with frequencies 8, 17, 0, 10. Each class is lower < mass ≤ upper. Construct the labelled cumulative-frequency table and actual diagram, including the correct initial zero point, every upper-boundary point and the final total. Use consistent numerical scales. Explain any zero-frequency interval and why class midpoints are not the required plotting positions. State whether you use a smooth nondecreasing guide or a declared straight-segment guide.
Give me a hint
For each upper boundary ask how many observations have accumulated so far; begin at the lower-support boundary with zero.
Compare my reasoning
- Accumulate the class frequencies from zero: 0+8=8; 8+17=25; 25+0=25; 25+10=35. Each new total includes all observations up to that upper boundary.
- The cumulative table at boundaries 100, 120, 150, 190, 250 is 0, 8, 25, 25, 35. Plot (100,0), (120,8), (150,25), (190,25), (250,35). The initial point is (100,0), set by the actual lower class boundary; the final cumulative count is 35.
- Label the horizontal axis mass (g) and the vertical axis Cumulative frequency. Preserve actual boundary spacings and plot at upper boundaries, because each running total counts observations up to that boundary. Join with a nondecreasing guide; a declared straight-segment guide is one reproducible choice.
- The zero-frequency class 150 < mass ≤ 190 gives a flat guide at count 25. An inverse reading at that count can lie anywhere along the plateau; do not invent one unique threshold.
Class frequencies 8, 17, 0, 10; cumulative counts 0, 8, 25, 25, 35 at boundaries 100, 120, 150, 190, 250 g; total 35. Required plotted pairs: (100,0), (120,8), (150,25), (190,25), (250,35). The guide is flat over [150,190] and its inverse there is not unique. Construct the actual labelled nondecreasing diagram on uniform numerical axes; do not plot class midpoints.
Look for these in your work
- Show the complete frequency/cumulative table and verify the final total.
- Plot the actual lower-support zero point and all upper-boundary pairs on calibrated labelled axes.
- Use a nondecreasing guide and explain any flat interval without inventing a unique inverse.
The complete continuous sample measures time. At boundaries 0, 5, 15, 30, 60 min, the supplied cumulative counts are 0, 9, 25, 46, 64. Recover the class frequencies before drawing. Construct the labelled cumulative-frequency table and actual diagram, including the correct initial zero point, every upper-boundary point and the final total. Use consistent numerical scales. Explain any zero-frequency interval and why class midpoints are not the required plotting positions. State whether you use a smooth nondecreasing guide or a declared straight-segment guide.
Give me a hint
For each upper boundary ask how many observations have accumulated so far; begin at the lower-support boundary with zero.
Compare my reasoning
- Recover consecutive class frequencies by differences: 9−0=9; 25−9=16; 46−25=21; 64−46=18. These differences isolate the observations added by each class.
- The cumulative table at boundaries 0, 5, 15, 30, 60 is 0, 9, 25, 46, 64. Plot (0,0), (5,9), (15,25), (30,46), (60,64). The initial point is (0,0), set by the actual lower class boundary; the final cumulative count is 64.
- Label the horizontal axis time (min) and the vertical axis Cumulative frequency. Preserve actual boundary spacings and plot at upper boundaries, because each running total counts observations up to that boundary. Join with a nondecreasing guide; a declared straight-segment guide is one reproducible choice.
- All class frequencies are positive, so every consecutive endpoint total increases. Check that the guide never decreases or overshoots the final total; a drawn route between endpoints is not exact knowledge of raw positions within a class.
Class frequencies 9, 16, 21, 18; cumulative counts 0, 9, 25, 46, 64 at boundaries 0, 5, 15, 30, 60 min; total 64. Required plotted pairs: (0,0), (5,9), (15,25), (30,46), (60,64). Construct the actual labelled nondecreasing diagram on uniform numerical axes; do not plot class midpoints.
Look for these in your work
- Show the complete frequency/cumulative table and verify the final total.
- Plot the actual lower-support zero point and all upper-boundary pairs on calibrated labelled axes.
- Use a nondecreasing guide and explain any flat interval without inventing a unique inverse.
The complete continuous sample measures temperature. The consecutive class boundaries are -6, -2, 4, 10, 18 °C, with frequencies 5, 15, 20, 10. Each class is lower < temperature ≤ upper. Construct the labelled cumulative-frequency table and actual diagram, including the correct initial zero point, every upper-boundary point and the final total. Use consistent numerical scales. Explain any zero-frequency interval and why class midpoints are not the required plotting positions. State whether you use a smooth nondecreasing guide or a declared straight-segment guide.
Give me a hint
For each upper boundary ask how many observations have accumulated so far; begin at the lower-support boundary with zero.
Compare my reasoning
- Accumulate the class frequencies from zero: 0+5=5; 5+15=20; 20+20=40; 40+10=50. Each new total includes all observations up to that upper boundary.
- The cumulative table at boundaries -6, -2, 4, 10, 18 is 0, 5, 20, 40, 50. Plot (-6,0), (-2,5), (4,20), (10,40), (18,50). The initial point is (-6,0), set by the actual lower class boundary; the final cumulative count is 50.
- Label the horizontal axis temperature (°C) and the vertical axis Cumulative frequency. Preserve actual boundary spacings and plot at upper boundaries, because each running total counts observations up to that boundary. Join with a nondecreasing guide; a declared straight-segment guide is one reproducible choice.
- All class frequencies are positive, so every consecutive endpoint total increases. Check that the guide never decreases or overshoots the final total; a drawn route between endpoints is not exact knowledge of raw positions within a class.
Class frequencies 5, 15, 20, 10; cumulative counts 0, 5, 20, 40, 50 at boundaries -6, -2, 4, 10, 18 °C; total 50. Required plotted pairs: (-6,0), (-2,5), (4,20), (10,40), (18,50). Construct the actual labelled nondecreasing diagram on uniform numerical axes; do not plot class midpoints.
Look for these in your work
- Show the complete frequency/cumulative table and verify the final total.
- Plot the actual lower-support zero point and all upper-boundary pairs on calibrated labelled axes.
- Use a nondecreasing guide and explain any flat interval without inventing a unique inverse.
Common mistakes
- Plotting class midpoints instead of upper boundaries and omitting the initial zero point.
- Spacing unequal measurement intervals equally on a numerical axis.
- Forcing a unique inverse measurement from a flat cumulative interval.
What can you explain now?
A cumulative guide is flat at count 12 from x=4 to x=9. Does an inverse reading at cumulative count 12 recover one unique x?
Compare with the explanation
No. Every x on the flat interval [4,9] has that cumulative-guide value.
No observations are added across that class interval, so the graph does not select a unique threshold from that plateau.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain how you would move between a class-frequency table, its running totals and the plotted cumulative guide, including a zero class.
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.