Question

Find the mean:

Class interval:	0-6	6-12	12-18	18-24	24-30
Frequency:	6	8	10	9	7

Answer 1

Let’s consider the assumed mean (A) = 15

From the table it’s seen that,

A = 15 and h = 6

Mean = A + h x (\(\frac{Σf_i u_i}{N}\))

= 15 + 6 x (\(\frac{3}{40}\))

= 15 + 0.45

= 15.45