NCERT Class 7 Mathematics

DATA HANDLING 71

Let us look at another example more related to us.

EXAMPLE 10 A mathematics teacher wants to see, whether the new technique of teach-
ing she applied after quarterly test was effective or not. She takes the
scores of the 5 weakest children in the quarterly test (out of 25) and in
the half yearly test (out of 25):
Students Ashish Arun Kavish Maya Rita
Quarterly 10 15 12 20 9
Half yearly 15 18 16 21 15

SOLUTION Since there seems to be a marked improvement in most of
the students, the teacher decides that she should continue to
use the new technique of teaching.
Can you think of a few more situtions where you could use double
bar graphs?

1. The bar chart (Fig 3.2) shows the result of a survey to test water resistant watches
   made by different companies.
   Each of these companies claimed that their watches were water resistant. After a
   test the above results were revealed.

0

2

Jan Feb.

March

April May

Scale : 1 unit = 1 hour of sunshine

4

6

8

June July

August

Sept. Oct. Nov. Dec.

Aberdeen

Margate

House of sunshine

Fig 3.1

TRY THESE