Question

The pie diagram shows the percentage of persons according to the blood group. Answer the following question: Find the measurement of central angle for blood group A.

Answer 1

Hint: Let us assume a whole pie chart. Any pie chart has sections in it. We know, each section is formed by three main parts that are arc length, section area and section angle. These all sections together constitute the whole circle of pie charts. Now, the arc length is a fraction of the total circumference of the circle, the section area is a fraction of the whole area of the circle and the section angle is a fraction of total angle which is ${360^ \circ }$ . Suppose the section is $x\% $ of the pie chart, then each of these parts is $x\% $ of the whole. So, the central angle or the section angle is calculated by $x\% $ of ${360^ \circ }$ .

Complete step-by-step answer:
The given data in the pie chart can be shown in the tabular form:

Blood Group	Percentage
O	45
A	20
B	30
AB	5
Total	100

The total central angle of a circle or pie chart is ${360^ \circ }$ .
So, the central angle of blood group A can be calculated by:
Central angle $ = \dfrac{{20}}{{100}} \times 360 = 72$
Therefore, the central angle for blood group A is 72.

Note: As we know, the complete central angle of circle is ${360^ \circ }$ . So, we need to be very careful with the values we are substituting to get the value of the central angle. Also, we should be able to read the pie charts if in case values are not shown and also, our first strategy to solve the questions of pie chart should be identifying the number of sections or sectors of the whole circle.