The following errors and irregularities were discovered in the audit of the Trusty Company:

1. Cash was stolen from the cashier's desk.

2. Bad debt losses were high because credit was approved by salespersons.

3. Several checks were not recorded in the check register.

4. Many sales invoices contained mathematical errors.

5. Cash sales were pocketed by salespersons.

6. Terminated employees were kept on the payroll.

7. Cash was misappropriated by the cashier who also reconciled the bank statement.

8. An unauthorized shipment was made from the warehouse.

9. The customer's accounts receivable ledger did not agree with accounts receivable control.

10. An unauthorized check was issued.

11. Several vouchers were improperly coded.

12. Several sales invoices were billed at prices different than those authorized.

Required:

a. Identify the internal control principle(s) that was (were) violated in each case.

b. Indicate the control procedure that will prevent the error or irregularity.