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Question
In the first proof reading of a book containing 300 pages the following distribution of misprints was obtained:
| No. of misprints per page (x) | 0 | 1 | 2 | 3 | 4 | 5 |
| No. of pages (f) | 154 | 95 | 36 | 9 | 5 | 1 |
Find the average number of misprints per page.
Solution
Let the assumed mean (A) = 2
| No. of misprints per page (x1) | No. of pages(f1) |
u1 = x1 - A = x1 - 2 |
f1u1 |
| 0 | 154 | -2 | -308 |
| 1 | 95 | -1 | -95 |
| 2 | 36 | 0 | 0 |
| 3 | 9 | 1 | 9 |
| 4 | 5 | 2 | 10 |
| 5 | 1 | 3 | 3 |
| N = 300 | `sumf_1"u"_1=381` |
Average number of mis prints per day `=A+(sumf_1"u"_1)/N`
`=2+(-381)/300`
`=2-381/300`
`=(600-381)/300`
`=219/300`
= 0.73
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