Question

Find the mean of each of the following frequency distributions :

Class interval:	0−6	6−12	12−18	18−24	24−30
Frequency:	7	5	10	12	6

Answer 1

Let the assumed mean be A = 15 and h = 6.

We know that mean,

Now, we have.

Putting the values in the above formula, we get

Hence, the mean is 15.75.