Question

EXERCISE - 14.1
1.
A survey was conducted by a group of students as a part of their environment awareness
programme, in which they collected the following data regarding the number of plants in
20 houses in a locality. Find the mean number of plants per house
8-10 10-12
6.8
4-6
2.4
12-14
3
0.2
Number of plants
2
6
5
1
2
1
Number of houses​

Answer 1

ANSWER

No. of plants No. of houses (f

i

) Mid point (X

i

) f

i

x

i

0−2 1 1 1

2−4 2 3 6

4−6 1 5 5

6−8 5 7 35

8−10 6 9 54

10−12 2 11 22

12−14 3 13 39

Total 20 162

Calculating mean, we get

Mean,

x

ˉ

=

n

1

∑f

i

x

i

Here, n=20,∑f

i

x

i

=162

Therefore, Mean,

x

ˉ

=

20

162

=8.1 plants

We have used direct method because numerical values of f and x are small.