Question

What is the minimum sample size needed to estimate the mean age of the books in...

What is the minimum sample size needed to estimate the mean age of the books in a library to within 2 months with 95% confidence if the standard deviation of the ages is thought to be about 60 months?

Homework Answers

Answer #1

Solution :

Given that,

standard deviation = = 60

margin of error = E = 2

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.960

Sample size = n = ((Z/2 * ) / E)2

= (1.960 * 60) / 2)2

=3457.44

= 3457

The minimum sample size = 3457

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