At the end of the current year, the accounts receivable account has a debit balance of $1,938,000 and sales for the year total $27,130,000. Determine the amount of the adjusting entry to provide for doubtful accounts under each of the following assumptions: a. The allowance account before adjustment has a debit balance of $13,200. Bad debt expense is estimated at 1/4 of 1% of sales. b. The allowance account before adjustment has a debit balance of $13,200. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $28,310. c. The allowance account before adjustment has a credit balance of $8,800. Bad debt expense is estimated at 1/2 of 1% of sales. d. The allowance account before adjustment has a credit balance of $8,800. An aging of the accounts in the customer ledger indicates estimated doubtful accounts of $73,000