RD Sharma Class 8 Maths Solutions Chapter 25 - Data Handling III

Pie charts are considered to be the easiest way to compare the given information, gauge the range of data to draw the final predictions. Hence this sort of graphical representation of data handling is often used to calculate the profit and loss in a business, marketing or sales materials used in a company and also to compare the percentage scores of students in a class. Retention of the data can be done best by pictorial representation and handling of data in this way is quite handy also. From a more pragmatic viewpoint, pictorial representation often makes the information more accessible to the majority especially when there is a small amount of data.. The concept of pie charts makes it easy for all to represent any data in their day-to-day life. This is the preferred way of representation in mass media also for its easy approach.

The provided data is first converted to the degrees for representing them in a circle which has a total of 360 degrees. This is done by dividing the data by the total value of data and then multiplying by 360 degrees. The other way is to divide the frequency by the total frequency and then multiply by 100. The concept behind these calculations is that the data are just the portions of the angle of a circle which is 360 degrees or the portion of total percentage of 100. Representation of the different sections is done either by different colors, shades or patterns.

A neat and colorful pie chart is the best way of representation. A neat proper presentation also makes a good impression on the teacher and this first impression can bring good marks for the students. 

It can be prepared by using the following steps:

• First all the values should be added to get the total quantity of the data given

• The percentage of each piece of data to be calculated by dividing each value by the total value and multiplying by 100

• Each degree of the sector is to be determined by dividing the frequency of each by the total frequency and multiplying by 360.

• Proceed to draw the circle with the calculated angles by using a protractor.

• An appropriate title should be mentioned.

• Mentioning the source of information of the data draws a good impression.

• An index of the different colors and patterns used in the pie chart should be mentioned. 

Pie chart has an additional advantage of representation of a data than the other forms of representation because of the following reasons:

• A visual effective tool for communication which makes the data legible to an uninformed observer

• This is probably the easiest way for the observed to understand the information at a glance

• Comparison of any data and retaining them in the mind of the observer is possible with this representation.

However, like all other good things, this also has some disadvantages. They are summed up as follows:

• When too much data is provided this representation gets clumsy and less effective.

• Only one data set can be represented at a time. No two sets can be represented by a single chart

• Often decisions made on visual impact give inaccurate results.

• This representation cannot be used for a set of negative data.

• This data is often manipulated easily so cannot always be reliable.