Question

Suppose that the thickness of sheets of a certain weight of book paper have mean .1 mm and a standard deviation of .003 mm. A particular text- book will be printed on 370 sheets of this paper. Find sensible values for the mean and standard deviation of the thicknesses of copies of this text (excluding, of course, the book’s cover).

Answer 1

The sensible values for the mean = 37 mm

The sensible values for standard deviation = 1.11

Explanation:

Data provided in the question:

Mean thickness of a certain weight of book paper = 0.1 mm

Standard deviation, σ = 0.003 mm

Total number of sheets to be printed, n = 370 sheets

Now,

The sensible values for the mean = n × Mean

= 370 × 0.1

= 37 mm

and,

standard deviation = √variance

also,

Variance = n² × σ²

= 370² × 0.003²

= 1.2321

thus,

The sensible values for standard deviation = √1.2321

= 1.11