The auditors are using mean-per-unit sampling to evaluate the reasonableness of the book value of the accounts receivable of Smith, Inc. Smith has 10,000 receivable accounts with a total book value of $800,000. The auditors estimate the population's standard deviation as being equal to $25. After examining the overall audit plan, the auditors believe that the account's tolerable misstatement is $40,000, and that a risk of incorrect rejection of .10 (risk coefficient = 1.64) and a risk of incorrect acceptance of .15 (risk coefficient = 1.04) should be used. Calculate the required sample size.