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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 |
Solution
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)
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