Question

The following pie diagram shows the percentage of persons according to blood group in a blood group checking camp. Answer the following questions:

1. Find the measure of the central angle for each blood group.
2. Find the total number of persons if there are 600 persons with blood group B.

Answer 1

Given: % of a blood group A = 20%

% of a blood group B = 30%

% of a blood group O = 45%

% of a blood group AB = 5%

∴ The sum of percentage of all four blood group = % of A + % of B + % of O + % of AB

= 20 + 30 + 45 + 5

= 100%

a. Central angle = `"Percentage of blood group"/100 xx 360`

Central angle for blood group A = `20/100 xx 360`

= 2 × 36

= 72°

Central angle for blood group B = `30/100 xx 360`

= 3 × 36

= 108°

Central angle for blood group O = `45/100 xx 360`

= `45/10 xx 36`

= `9/2 xx 36`

= 9 × 18

= 162°

Central angle for blood group AB = `5/100 xx 360`

= `1/2 xx 36`

= 18°

b. The total number of persons of blood group B are 600 and the central angle of blood group B is 108°.

∴ Total number of persons = `600/108 xx 360`

= `600/27 xx 90`

= `600/3 xx 10`

= `6000/3`

= 2000

∴ Total number of persons are 2000.