← Back to the activity

Year 9 Maths — Grouped data, histograms and pie charts

Group data into class intervals, read a histogram, and work out the angles in a pie chart.

Name: ________________________

Before you start

This pie chart shows what a class of 40 children picked for their club. Find out what each slice is and how wide its angle is — nothing here is right or wrong.

1234
  1. 1. Reading — 90°, so 10 children
  2. 2. Sport — 90°, so 10 children
  3. 3. Music — 108°, so 12 children
  4. 4. Art — 72°, so 8 children

The four angles add up to 360°, one whole turn. Music is the biggest slice because 12 out of 40 is the biggest share — and 12/40 of 360° really is 108°.

  1. 1.Put these pie-chart sectors in order by the size of their angle, smallest first.

    • 1/3 of the whole
    • 1/8 of the whole
    • 1/12 of the whole
    • 1/4 of the whole
    • 1/6 of the whole

  2. 2.A pie chart shows 200 people. One sector measures 72 degrees. How many people does that sector stand for?

  3. 3.What is the main difference between a bar graph and a histogram?

    • a) A histogram has no gaps between its bars, because its classes run on from each other
    • b) A bar graph cannot show how many there are of anything
    • c) A histogram always has more bars than a bar graph
    • d) A histogram has to be drawn in colour

  4. 4.A class interval runs from 15 to 25. What is its midpoint?

  5. 5.A class interval runs from 20 to 30. What is its class size?

  6. 6.These marks are grouped in intervals of 10 starting at 0: 5, 12, 18, 23, 27, 31, 34, 38, 45. How many marks fall in the interval 30 to 40?

  7. 7.Match each share of the whole to the angle of its sector in a pie chart, in degrees.

    • Half
    • A quarter
    • A third
    • A fifth
    • A tenth
    • 120
    • 36
    • 72
    • 180
    • 90

  8. 8.A pie chart is split between 4 subjects with an equal share each. What angle does each sector take, in degrees? Give just the number.

Answer key — Year 9 Maths — Grouped data, histograms and pie charts

  1. 1. 1. 1/12 of the whole 2. 1/8 of the whole 3. 1/6 of the whole 4. 1/4 of the whole 5. 1/3 of the whole
  2. 2. 40
  3. 3. a) A histogram has no gaps between its bars, because its classes run on from each other
  4. 4. 20
  5. 5. 10
  6. 6. 3
  7. 7. Half → 180; A quarter → 90; A third → 120; A fifth → 72; A tenth → 36
  8. 8. 90