Pie charts
Answers are for parents and teachers.
1
A survey of 20 children gave: bus 9, walking 6, bicycle 3, car 2. Write each count as a fraction of the total in simplest form and check the sum is 1.
9/20, 6/20 = 3/10, 3/20, 2/20 = 1/10. 9/20 + 6/20 + 3/20 + 2/20 = 20/20 = 1.
2
Find the angle for 1/2, 1/4, 1/10 and 1/20 of a circle.
180°, 90°, 36°, 18°.
3
40% of 150 children like reading. How many is that?
40/100 × 150 = 60 children.
4
10 children chose red, 5 blue and 15 yellow. Find the angle of each sector.
Total 30. 360 ÷ 30 = 12° each. Red: 10 × 12 = 120°. Blue: 5 × 12 = 60°. Yellow: 15 × 12 = 180°. Check: 120 + 60 + 180 = 360.
5
Karim says a pie chart can have sectors of 50%, 30% and 30%. Is he right?
No. 50 + 30 + 30 = 110%, which is more than 100%.