Question

The following table gives the number of children of 150 families in a village. Find the average number of children per family.

No. of children (x)	0	1	2	3	4	5
No. of families (f)	10	21	55	42	15	7

Answer 1

Let the assumed mean (A) = 2

No. of children (x1)	No of families(f1)	u1 = x1 - A = x1 - 2	f1u1
0	10	-2	-20
1	21	-1	-21
2	55	0	0
3	42	1	42
4	15	2	30
5	7	3	21
	N = 150		`sumf_1u_1=52`

Average number of children for family `=A+(sumf_1"u"_1)/N`

`=2+52/150`

`=(300+52)/150`

`=352/150`

= 2.35(Approx)