Question

Draw a pie-diagram representing the relative frequencies (expressed as percentage) of the eight classes as given below:
12.6, 18.2, 17.5, 20.3, 2.8, 4.2, 9.8, 14.7

Answer 1

We know:
Central angle of a component = (component value/sum of component values x 360)
Here, total amount = 100.1%
Thus, central angle for each component can be calculated as follows:
 

Item	Amount (in %)	Sector angle
Class I	12.6	12.6/100.1 x 360 = 45.3
Class II	18.2	18.2/100.1 x 360 = 65.5
Class III	17.5	17.5/100.1 x 360 = 62.9
Class IV	20.3	20.3/100.1 x 360 = 73
Class V	2.8	2.8/100.1 x 360 = 10.1
Class VI	4.2	4.2/100.1 x 360 = 15.1
Class VII	9.8	9.8/100.1 x 360 = 35.2
Class VIII	14.7	14.7/100.1 x 360 = 52.9

Total = 100.1%

Now, the pie chat representing the given data can be constructed by following the steps below:
Step 1 : Draw circle of an appropriate radius.
Step 2 :  Draw a vertical radius of the circle drawn in step 1
Step 3 : Choose the largest central angle. Here the largest central angle is 73^o. Draw a sector with the central angle 73^o in such a way that one of its radii coincides with the radius drawn in step 2 and another radius is in its counter clockwise direction.
Step 4 : Construct other sectors representing the other items in the clockwise sense in descending order of magnitudes of their central angles.
​Step 5 : Shade the sectors with different colours and label them, as shown as in the figure below.​​