Final answer:
Proper controls related to uncollectible accounts include segregation of responsibilities, establishing guidelines for determining allowance for uncollectible accounts, and generating an accounts receivable aging report.
Step-by-step explanation:
The proper controls related to uncollectible accounts include segregation of responsibilities so that no one has the opportunity to write off an account to cover up stolen cash, establishment of thorough guidelines for determining the amount of an allowance for uncollectible accounts, and generation of an accounts receivable aging report to analyze customer balances and payment delays. However, mathematical verification of the cash receipts journal and the accounts receivable ledger is not specifically mentioned as a proper control.