A prospective purchaser of a toy store wishes to estimate the mean dollar amount of sales per customer at a toy store located at an airline terminal. Based on information collected from similar airports, the standard deviation of such sales amount is estimated to be $3.20. What is the minimum size random sample that the store purchaser should collect if he wants to estimate the mean sales amount within $1.50 and with 99% percent confidence? Assume that the amount spent per customer follows a normal distribution.