Level of Confidence, (1

)

100%

Area in Each Tail,

2

Critical Value,

z/2

90%

0.05

1.645

95%

0.025

1.96

99%

0.005

2.575

People were polled on how many books they read the previous year. Initial survey results indicate that s=13.5 books.

(a) How many subjects are needed to estimate the mean number of books read the previous year within

four books with 95% confidence? This 95% confidence level requires_____subjects.