Question

Calculate the mean of the following distribution using Assumed Mean Method

Class Interval	0 − 10	10 − 20	20 − 30	30 − 40	40 − 50
Frequency	5	7	15	28	8

Answer 1

Assumed Mean (A) = 25

Class Interval	Mid value (x)	Frequency  (f)	d = x − A	fd
0 − 10	5	5	−20	−100
10 − 20	15	7	−10	−70
20 − 30	25	15	0	0
30 − 40	35	28	10	280
40 − 50	45	8	20	160
		`sumf` = 63		`sumf"d"` = 270

Arithmetic mean `(barx) = "A" + (sumf"d")/(sumf)`

= `25 + 270/63`

= 25 + 4.29

Assumed Mean = 29.29