Construct and interpret complete pie charts
Convert frequencies and whole-circle angles in both directions, construct labelled constant-radius sectors, and check the whole.
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
- Use fractions of a whole and direct proportional reasoning.
- Measure and construct an angle with a correctly aligned protractor.
- Recognise a complete turn as 360°.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
A category has 16 of a total 64 observations. Which angle represents it?
What you will learn
- Convert a category frequency to its fraction of a whole and its sector angle.
- Recover frequencies or an absent angle from consistent supplied sector information.
- Construct or complete a labelled circle and check both angle and frequency totals.
Construct and label a pie chart for counts A: 14; B: 21; C: 7. Find the total, each fraction and each sector angle, then show the actual complete circle. Show the frequency↔angle calculation for every category, check the 360° and frequency totals, and identify the greatest category. Use a constant radius and a consistent direction around the circle.
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 complete labelled constant-radius sector construction
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.
State your own conclusion from the complete representation.
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.
Make the whole explicit
A pie chart represents one whole sample by a complete circle. If a category has frequency f in a total N, its fraction of the whole is f/N and its sector angle is 360°×f/N. Add the frequencies first when the total is not stated. The same circle radius must be used for every sector so the angles genuinely describe parts of one whole.
A frequency and an angle are different quantities. The angle is measured in degrees; the frequency counts observations. Use the fraction of the total to move between them, rather than treating a count as a degree value. Two circles with different sample sizes may show the same proportion even though the underlying category counts differ.
Construct actual sectors
Draw a circle with a fixed centre and choose a starting radius. Align the protractor centre with the circle centre, its baseline with the current radius, and measure each calculated sector consistently around the circle. Draw the new radius and label its category. Where no initial orientation is supplied, your chosen starting direction does not change the data represented.
Check that the measured sectors make a complete 360° turn without gaps or overlaps. Keep the labels attached to the correct sectors and use the stated category order consistently. A table of calculated angles prepares the construction but does not replace the actual labelled circle. Small drawing discrepancies should be assessed against the instrument scale, not described as exact raw counts.
Read in reverse and check consistency
If an angle θ and total N are given, recover the frequency as N×θ/360°. If one sector angle is absent, subtract the sum of all known sector angles from 360° before converting its fraction. A supplied unlabelled wedge may be part of the original diagram, but its unknown numerical angle must still be worked out rather than assumed from its appearance.
Add recovered counts and compare them with N, and add the angles to check 360°. For exact data about whole individuals, a fractional recovered count signals an inconsistency to investigate rather than a value to round silently. The greatest angle within one complete circle corresponds to the greatest category frequency; its physical size in a different-sized circle is not a direct count comparison.
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 supplied pie chart totals 72 individuals. One sector is 150°. What count does it represent?
Worked example
Construct and label a pie chart for counts A: 14; B: 21; C: 7. Find the total, each fraction and each sector angle, then show the actual complete circle. Show the frequency↔angle calculation for every category, check the 360° and frequency totals, and identify the greatest category. Use a constant radius and a consistent direction around the circle.
Show the worked solution
- The whole sample is 42. Add the counts to check it: 14+21+7=42. Use this same whole as the denominator for every category.
- Calculate angle=360°×frequency/42: A: 360×14/42=120°; B: 360×21/42=180°; C: 360×7/42=60°. Each calculation takes the category’s fraction of one whole turn.
- The fractions are A: 1/3; B: 1/2; C: 1/6. Construct or complete the constant-radius sectors in consistent listed order with angles 120, 180, 60 degrees; align the protractor at the centre and each current radius, then draw and label each new boundary.
- Check that 120+180+60=360° and the frequencies total 42. B has the largest frequency 21 and hence the largest angle 180° within this circle.
Answer Total 42; frequencies A: 14; B: 21; C: 7; fractions A: 1/3; B: 1/2; C: 1/6; angles A: 120; B: 180; C: 60 degrees, summing to 360°. B is greatest. The answer includes the actual labelled complete circle, not just the calculation table.
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.
Construct and label a pie chart for counts Walk: 15; Cycle: 9; Bus: 18; Car: 12. Find the total, each fraction and each sector angle, then show the actual complete circle. Show the frequency↔angle calculation for every category, check the 360° and frequency totals, and identify the greatest category. Use a constant radius and a consistent direction around the circle.
Give me a hint
Use a fraction of 360° for each category; for one missing angle, complete the whole before converting its count.
Compare my reasoning
- The whole sample is 54. Add the counts to check it: 15+9+18+12=54. Use this same whole as the denominator for every category.
- Calculate angle=360°×frequency/54: Walk: 360×15/54=100°; Cycle: 360×9/54=60°; Bus: 360×18/54=120°; Car: 360×12/54=80°. Each calculation takes the category’s fraction of one whole turn.
- The fractions are Walk: 5/18; Cycle: 1/6; Bus: 1/3; Car: 2/9. Construct or complete the constant-radius sectors in consistent listed order with angles 100, 60, 120, 80 degrees; align the protractor at the centre and each current radius, then draw and label each new boundary.
- Check that 100+60+120+80=360° and the frequencies total 54. Bus has the largest frequency 18 and hence the largest angle 120° within this circle.
Total 54; frequencies Walk: 15; Cycle: 9; Bus: 18; Car: 12; fractions Walk: 5/18; Cycle: 1/6; Bus: 1/3; Car: 2/9; angles Walk: 100; Cycle: 60; Bus: 120; Car: 80 degrees, summing to 360°. Bus is greatest. The answer includes the actual labelled complete circle, not just the calculation table.
Look for these in your work
- Calculate every category fraction, frequency and angle in the required direction.
- Construct or complete the labelled constant-radius circle without gaps or overlap.
- Check both whole totals and justify the greatest category without silently rounding whole-person data.
The supplied complete circle represents 90 individuals, with sectors Q: 72°; R: 108°; S: 144°; T: 36°. All four sector angles are supplied: recover every category frequency. Complete or redraw the labelled circle with those category sectors. Show the frequency↔angle calculation for every category, check the 360° and frequency totals, and identify the greatest category. Use a constant radius and a consistent direction around the circle.
Give me a hint
Use a fraction of 360° for each category; for one missing angle, complete the whole before converting its count.
Compare my reasoning
- The whole sample is 90. Use the given total for each reverse frequency calculation; every sector describes a fraction of that same whole.
- Calculate frequency=90×angle/360: Q: 90×72/360=18; R: 90×108/360=27; S: 90×144/360=36; T: 90×36/360=9.
- The fractions are Q: 1/5; R: 3/10; S: 2/5; T: 1/10. Construct or complete the constant-radius sectors in consistent listed order with angles 72, 108, 144, 36 degrees; align the protractor at the centre and each current radius, then draw and label each new boundary.
- Check that 72+108+144+36=360° and the frequencies total 90. S has the largest frequency 36 and hence the largest angle 144° within this circle.
Total 90; frequencies Q: 18; R: 27; S: 36; T: 9; fractions Q: 1/5; R: 3/10; S: 2/5; T: 1/10; angles Q: 72; R: 108; S: 144; T: 36 degrees, summing to 360°. S is greatest. The answer includes the actual labelled complete circle, not just the calculation table.
Look for these in your work
- Calculate every category fraction, frequency and angle in the required direction.
- Construct or complete the labelled constant-radius circle without gaps or overlap.
- Check both whole totals and justify the greatest category without silently rounding whole-person data.
The supplied complete circle represents 80 individuals, with sectors Red: 81°; Blue: unlabelled angle; Green: 135°; Gold: 45°. One numerical angle is missing: recover it and every category frequency. Complete or redraw the labelled circle with those category sectors. Show the frequency↔angle calculation for every category, check the 360° and frequency totals, and identify the greatest category. Use a constant radius and a consistent direction around the circle.
Give me a hint
Use a fraction of 360° for each category; for one missing angle, complete the whole before converting its count.
Compare my reasoning
- The whole sample is 80. First recover the blank angle: 360°−(81+135+45)°=99°. The sector angles must complete one whole turn.
- Calculate frequency=80×angle/360: Red: 80×81/360=18; Blue: 80×99/360=22; Green: 80×135/360=30; Gold: 80×45/360=10.
- The fractions are Red: 9/40; Blue: 11/40; Green: 3/8; Gold: 1/8. Construct or complete the constant-radius sectors in consistent listed order with angles 81, 99, 135, 45 degrees; align the protractor at the centre and each current radius, then draw and label each new boundary.
- Check that 81+99+135+45=360° and the frequencies total 80. Green has the largest frequency 30 and hence the largest angle 135° within this circle.
Total 80; frequencies Red: 18; Blue: 22; Green: 30; Gold: 10; fractions Red: 9/40; Blue: 11/40; Green: 3/8; Gold: 1/8; angles Red: 81; Blue: 99; Green: 135; Gold: 45 degrees, summing to 360°. Green is greatest. The answer includes the actual labelled complete circle, not just the calculation table.
Look for these in your work
- Calculate every category fraction, frequency and angle in the required direction.
- Construct or complete the labelled constant-radius circle without gaps or overlap.
- Check both whole totals and justify the greatest category without silently rounding whole-person data.
Common mistakes
- Using a frequency as an angle without dividing by the total.
- Leaving a gap or overlap, or measuring successive sectors from inconsistent baselines.
- Rounding a fractional whole-person result to conceal inconsistent exact data.
What can you explain now?
A supplied circle contains three known sector angles and one blank label. What two checks should follow recovery of the missing angle and all frequencies?
Compare with the explanation
Check that the angles total 360° and the frequencies total the stated sample size.
These check the whole geometrically and numerically. For whole individuals, an exact fractional frequency also needs investigating.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Make it stick
State both frequency-to-angle and angle-to-frequency calculations, then describe how to complete and check a labelled pie chart.
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.