1. Chapter 8: Estimation Section 4: Choosing the Sample Size

2. REVIEW  Walter jogs 3 miles and has recorded his times to run the 3 miles. For the 90 times he recorded, his mean time is 22.50 minutes with a standard deviation of 2.40 minutes. Find a 99% confidence interval. n = 90 = 22.50 = 2.40 c =.99 z c = 2.58

3. To compute the sample size for estimating n = Example A wildlife study is designed to find the mean weight of salmon caught by an Alaskan fishing company. As a preliminary study, a random sample of 50 freshly caught salmon is weighed. The sample standard deviation is 2.15 pounds. How large a sample should be taken to be 99% confident that the sample mean is within 0.20 pound of the true mean weight ?

4. To compute the sample size for estimating p n = To compute sample size when p is not given n =

5. Example  The department of public health wants to estimate the proportion of children who require corrective lenses for their vision. The health department wants to be 99% sure that the point estimate for p will be in error either way by less than 0.03. How large a sample should the health department use?  If a preliminary random sample of 100 children indicates that 23 require corrective lenses, how large a sample should the health department use?