Question

EXERCISE 14.1
1. A survey was conducted by a group of students as a part of their environment awaren
programme, in which they collected the following data regarding the number of plan
20 houses in a locality. Find the mean number of plants per house.
Number of plants
0-2
2-4
4-6
6-8
8-10
10-12
12-14
Number of houses
5
6
2
نی
Which method did you use for finding the mean, and why? Direct method
​

Answer 1

Answer:

To find the class mark (xi) for each interval the following relation is used.class mark xi =upper limit+ lower limit x and f (x) can be calculate as follows

2

Numbers of plants,

0-2

2-4

4-6

6-8

8-10

10-12

12-14

total

Numbers of houses (f)

1

2

1

5

6

2

3

total 20

xi

1

3

5

7

9

11

13

fixi

1✖1=1

2✖3=6

1✖5=5

5✖7=35

6✖9=54

2✖11=22

3✖13=34

total 162