At the end of the current year, the accounts receivable account has a debit balance of $1,132,000 and sales for the year total $12,840,000.

1. The allowance account before adjustment has a debit balance of $15,300. Bad debt expense is estimated at 3/4 of 1% of sales.
2. The allowance account before adjustment has a debit balance of $15,300. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $49,000.
3. The allowance account before adjustment has a credit balance of $8,700. Bad debt expense is estimated at 1/2 of 1% of sales.
4. The allowance account before adjustment has a credit balance of $8,700. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $72,200.

Determine the amount of the adjusting entry to provide for doubtful accounts under each of the assumptions (a through d) listed above.