Question

The mean of the following frequency distribution is 25.2. Find the missing frequency x.

Class
0 - 10
10 - 20
20 – 30
30 – 40
40 - 50

Frequency
8
x
10
11
9​

Answer 1

Hope it helps.

If you have any query, feel free to ask.

Answer 2

Solution:-

Frequency Distribution Frequency Mid values F*M

0 - 10 8 5 40

10 - 20 x 15 15x

20 - 30 10 25 250

30 - 40 11 35 385

40 - 50 9 45 405

_____________________________________________________

Σf = 38+x Σfm = 1080+15x

______________________________________________________

Given Mean = 25.2

Mean = Σfm/Σf

25.2 = 1080+15x/38+x

25.2 × (38+x) = 1080+15x

957.6+25.2x = 1080+15x

25.2x - 15x = 1080 - 957.6

10.2x = 122.4

x = 122.4/10.2

x = 12

Missing frequency = 12 Answer