Mathematics
Pie charts
Class 8
Intermediate
About 15 min
Premium
Pie charts: a family's monthly budget
Share out a family's monthly income between food, rent, school fees and savings, and draw the budget as a pie chart.
Core concept
The angle of each slice is its share of the total × 360°
Topic: Pie charts
A family earns Rs 40,000 a month and plans how to spend it: food, rent, school fees, savings and other costs. A pie chart shows each item as a slice of a circle. The whole circle, 360°, stands for the whole income, so each item's slice is its share of the total times 360°. If food costs Rs 16,000 of Rs 40,000, its share is 16/40 = 0.4, and its slice is 0.4 × 360° = 144°.
What you will learn
- Work out the angle of each sector of a pie chart.
- Read percentages and fractions from a pie chart.
- Explain how slices change when one amount changes.
Before you start
- Fractions of an amount; angles round a point make 360°.
Materials
- A family budget or a list of monthly costs
Equipment
- A protractor and compasses
Procedure
- Tap − or + beside each item to change how many thousand rupees go to it.
- Watch the slices and the working: amount ÷ total × 360°.
- Record the family's budget of Rs 40,000, and find a slice that is a quarter of the pie and a slice that is 10%.
- Change the food money so that food is exactly half of the pie, and record it.
How this simulation is simplified
- Amounts are in thousands of rupees.