One of the purposes of an audit is to detect the presence of material errors, procedural errors, or errors in judgment in the

recording of accounting information. Suppose a CPA firm accounts are processed to conduct an audit of a firm in which accounts

are processed by two divisions, a retail division and a wholesale division. It is known that $60\%$ of all accounts are retail accounts. The

other $40\%$ are wholesale accounts. Furthermore, it is known that $10\%$ of all retail accounts and $5\%$ of all wholesale accounts contain

some type of accounting error.