to examine the required sample size needed to be able to estimate the mean dollars that each card holder will spend each month.

to examine the required sample size needed to be able to estimate the mean dollars that each card holder will spend each month. It would like to be within plus or minus $50 of the true mean with a 95% confidence level. The standard deviation is thought to be $750. How many card holders should be sampled? Your company charges a set dollar amount for each account in the sample.