For each of the following specific audit procedures, indicate the type of audit procedure(s) it represents: (1) inspection of records or documents, (2) inspection of tangible assets, (3) observation, (4) inquiry, (5) confirmation, (6) recalculation, (7) reperformance, (8) analytical procedures, (9) scanning, (1/7), and (9/7).
a. Sending a written request to the client's customers requesting that they report the amount owed to the client.
b. Examining large sales invoices for a period of two days before and after year-end to determine if sales are recorded in the proper period.
c. Agreeing the total of the accounts receivable subsidiary ledger to the accounts receivable general ledger account.
d. Discussing the adequacy of the allowance for doubtful accounts with the credit manager.
e. Comparing the current-year gross profit percentage with the gross profit percentage for the last four years.