At the end of the current year, the accounts receivable account has a debit balance of $947,000 and sales for the year total $10,740,000. The allowance account before adjustment has a credit balance of $12,800. Bad debt expense is estimated at 1/4 of 1% of sales. The allowance account before adjustment has a credit balance of $12,800. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $41,000. The allowance account before adjustment has a debit balance of $5,700. Bad debt expense is estimated at 3/4 of 1% of sales. The allowance account before adjustment has a debit balance of $5,700. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $47,300. Determine the amount of the adjusting entry to provide for doubtful accounts under each of the assumptions (a through d) listed above.