A pilot study has revealed a sample standard deviation of 16 for age of people in the work force. How large a sample must be chose to obtain an estimator of the mean that, with 95% confidence, will be correct to within 2 years?

Answer 1

Formula:
n = [(z-value * sd)/E]^2
...where n = sample size, z-value will be 1.96 using a z-table to represent 95% confidence, sd = 16, E = 2, ^2 means squared, and * means to multiply.

Plug the values into the formula and finish the calculation. Round your answer to the next highest whole number.

I hope this will help get you started.

Answer 2

A manufacturer of golf equipment wishes to estimate the number of left-handed golfers. How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of left-handed golfers is 8%