Question

If 82 pages had between 7 and 9 errors, what was the approximate total number of pages in the book?

A: 202 pages

B: 120 pages

C: 68 pages

D: 56 pages

Answer 1

120 pages

Explanation:

The mean number of error per page = 8 ; Standard deviation = 1

Given that :

82 pages has between 7 and 9 errors per page ;

Using the empirical rule :

7 = 8 - 1 = 1 standard deviation below the mean

9 = 8 + 1 = 1 standard deviation above the mean

1 standard deviation from the mean = 68%

Hence, 82 pages = 68%

Approximate total pages :

68% = 82

100% = total pages, x

0.68 = 82

1 = x

0.68x = 82

x = 82 / 0.68

x = 120.588

Hence, total number of pages is 120 pages