Question

28. An editor wants to estimate average the number of pages in bestselling novels, so that his estimate falls within 20 pages of the true average. Assuming that the standard deviation is 63 pages, how large a sample of bestselling novels is needed to achieve a. 90% confidence? b. 95% confidence? c. Identify the variable in this context d. Identify an individual in this context

Answer #1

solution:

the given information as follows:

the margin of error (E) = 20 pages

standard deviation = = 63 pages

a) we have to find the required sample size if confidence level is = 90% = 0.90

= 1-0.90 = 0.10

critical value of z =

formula for margin of error

so

so required sample size = 27 novels

b)

if confidence interval = 95%

we cannot sample in fraction so the required sample size =
**39 novels**

**c)**

**the variable in this context is the number of pages of
the novel.**

**d) the novels are the individual in this
context.**

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