Sam's Auto Parts uses the aging method to estimate bad debt expense. At the end of 2018, the company had an accounts receivable balance of $55,500 and a credit balance in the allowance for doubtful accounts of $8, 380. The company had the following analysis of accounts receivable at the end of 2018: Accounts Receivable Age Current 1-15 days past due 16-45 days past due 46-90 days past due Over 90 days past due Amount Proportion $ 40,000 11, 500 3, 100 4, 600 17.300 $ 75.500 Expected to Default 2% 3% 7% 15% 25% Sam's Auto Parts has a December 31 year end. Required: a) Calculate the desired ending balance of the allowance for doubtful accounts at the end of the year