A prospective purchaser wishes to estimate the mean dollar amount of sales per customer at a toy store located at an airlines terminal. Based on data from other similar airports, the standard...

A prospective purchaser wishes to estimate the mean dollar amount of sales per customer at a toy store located at an airlines terminal. Based on data from other similar airports, the standard deviation of such sales amounts is estimated to be about σ = $3:20. What size of random sample should be collected, as a minimum, if the purchaser wants to estimate the mean sales amount within $1:00 and with 99 percent confidence?