Question

People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 95​% ​confidence? Initial survey results indicate that sigma = 13.1 books.

A 95 % confidence level requires ____ subjects. ​(Round up to the nearest whole number as​ needed.)

Answer 1

Sample size = (Z $\alpha$ /2 * $\sigma$ / E)²

= ( 1.96 * 13.1 / 1)²

= 659.26

Sample size = 660 (Rounded up to nearest integer)

A 95% confidence level requires 660 subjects.