MATHEMATICS
● It is simple to read a pie chart. Just look at the required sector representing an item (or category) and read off the value. The pie chart has three sectors.
Look at the pie chart or circular graph above carefully. Study it then answer the questions in Exercise 1.
Exercise 1 1. Which of these is the best name for the graph? (a) Monthly expenditure (b) Andrew’s Monthly Expenditure (c) Mortgage and Fuel Expenditure (d) Andrew’s Fuel Expenses
2. What fraction of his expenditure was on mortgage? (a) ½ (b) 3/8 (c) ¼
3. What percent of the expenditure was fuel? (a) 25 (b) 37 ½ (c) 50
4. What percent does the entire pie chart represent? (a) 50 (b) 75 (c) 100
5. What fraction is the same as 37 ½ % ? (a) ½ (b) ¼
(c) 1/8
(d) 1/8 (d) 1/20
6. Which of these represents the least amount of money spent? (a) Mortgage (b) Food (c) Clothes (d) Fuel
In every pie chart there are sectors and each line passes through the center of the circle. A sector consists of two radii and an arc. The angles formed at the center of the circle total 360 degrees.
Example: In the month of August, there were 15 sunny days, 6 rainy days and 9 cloudy days. (a) Calculate the size of the angle for each sector (b) Check the correctness of your answer (b) Draw a circle graph to show the information.
Step 1: data.
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The number of cloudy days in August was 9/30 of the total number of days. Therefore, the degree measure of the sector for cloudy days is 3/10 x 360° = 108o
The number of sunny days in August was 15/30 of the total number of days. Therefore, the degree measure of the sector for partly-cloudy days is 1/2 of 360° = 180o
The number of rainy days in August was 6/30 of the total number of days. Therefore, the degree measure of the sector for the sunny days is 1/5 of 360° = 72o.
Step 2:
Calculate the degree measure of the sector for each piece of
Check that the sum of the degrees of the sectors is 360° 108° + 180° + 72° = 360°
Step 3: Draw a circle. Use a protractor to draw 3 sectors with the degree measures above. Label each sector. Give your circle graph a name.
Goodbye boys and girls. Until next week.