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 + \(\frac{\frac{N}{2}-F}{f}\)
\(24 = 20+\frac{55+\frac{x}{2}30}{x}\times10\)
4x = 275 + 5x – 300
4x – 5x = -25
-x = -25
x = 25
Therefore,
missing frequency = 25