III. Entries for Bad Debts $(12$ points$)$

The general ledger controlling account for Accounts Receivable has a balance of $$422,000$ at year$-$end before adjustment. By aging the individual customers' accounts using a percentage of accounts receivable, it was determined that the doubtful accounts amounted to $$10,000.$ Prepare the year$-$end adjusting entry for uncollectible accounts $($bad debt expense$)$ under each of the following independent assumptions.

a$.$ The Allowance for Doubtful Accounts has a credit balance of $$3,000.$

b$.$ The Allowance for Doubtful Accounts has a debit balance of $$2,000.$

c$.$ Sales during the period were $$2,000,000.$ Assuming the company wanted to estimate bad debt expense as $1\%$ of sales, what would be the required journal entry?

d$.$ A customer with an account balance of $$300$ has not paid the company for six months. Prepare the entry to write off this customer's account.