Example 7: A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 – 20, 20 – 30, . . ., 60 – 70, 70 – 100. Then she formed the following table:
A histogram for this table was prepared by a student as shown in Fig. 14.4.
Carefully examine this graphical representation. Do you think that it correctly represents the data?
Statistics – Bar graph, Histogram & Frequency polygon
In this tutorial you will learn how to draw few very important and basic graphs in statistics. It is bit lengthy video that covers different scenarios like uniform classes, varying width classes, continuous classes etc. It is a must watch video for every beginner to intermediate level of student of statistics. This video covers the following graphs:
- Bar graph
- Histogram
- Uniform width
- Varying width
- Frequency polygon
=> Introduction to Statistics – Must watch tutorial 
