Question

A survey was conducted that asked 1013 people how many books they had read in the past year. Results indicated that x overbarxequals=10.9 books and sequals=16.6 books. Construct a 90​% confidence interval for the mean number of books people read. Interpret the interval.

Answer 1

t critical value at 0.10 level with 1012 df = 1.646

90% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

10.9 - 1.646 * 16.6 / sqrt(1013) < < 10.9 + 1.646 * 16.6 / sqrt(1013)

10.042 < < 11.758

90% CI is (10.042 , 11.758 )

Interpretation = We are 90% confident that the mean number of books people read is between 10.042 and 11.758.