Calculate the missing frequency form the following distribution, it being given that the median of the distribution is 24.
Age in years: | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |
No. of persons: | 5 | 25 | ? | 18 | 7 |
Class interval | Frequency | Cumulative frequency |
0-10 | 5 | 5 |
10-20 | 25 | 30 (F) |
20-30 | x (f) | 30 + x |
30-40 | 18 | 48 + x |
40-50 | 7 | 55 + x |
N = 55 + x |
Given, Median = 24
Then median class = 20-30
l = 20, h = 10, f = x and F = 30
Median = l + 
24 = 20 + 
* 10
4x = 275 + 5x – 300
4x – 5x = -25
-x = -25
x = 25
Therefore, missing frequency = 25
7