The following distribution shows the daily pocket allowance of children of a locality
The mean pocket allowance is Rs 18. Find the missing frequency f
Daily pocket allowance (in Rs) | 11 - 13 | 13 - 15 | 15 - 17 | 17 - 19 | 19 - 21 | 21 - 23 | 23 - 25 |
Number of children | 7 | 6 | 9 | 13 | f | 5 | 4 |
The above given data can be represented in the form of table as below:
Class Interval | fi | xi | fixi |
11-13 | 7 | 12 | 84 |
13-15 | 6 | 14 | 84 |
15-17 | 9 | 16 | 144 |
17-19 | 13 | 18 | 234 |
19-21 | f | 20 | 20f |
21-23 | 5 | 22 | 110 |
23-25 | 4 | 24 | 96 |
∑fi = 44 + f | ∑fixi = 752 + 20f |
We can find the value of f as follows:
18
18( 44 + f ) = 752 + 20f
792 + 18f = 752 + 20f
2f = 40
F = 20
21