Question

Find the mean of the following frequency distribution : 

Class	25-35	35-45	45-55	55-65	65-75
Frequency	6	10	8	12	4

Answer 1

Class interval	Xi	fi	fixi
25-35	30	6	180
35-45	40	10	400
45-55	50	8	400
55-65	60	12	720
65-75	70	4	280
Total		40	1980

`barx =  (Σf_iX_i)/(Σ"f")`

`barx = 1980/40`

`barx = 49.5`

∴ Mean = 49.5