30. In order to determine whether internal control operated effectively to minimize errors of failure to post invoices to customer accounts receivable ledger accounts, the auditor would select from a sample of transactions from the population represented by the

a. receiving report file

b. customer order file

c. bill of lading file

d. sales invoice file

31. In order to gather evidence concerning proper credit approval of sales, the auditor would select a sample of transactions from the population represented by the

a. sales invoice file

b. subsidiary ledger file

c. customer order file

d. bill of lading