2. based on past experience as well as a review of the current accounts receivable detail, the credit department has determined that the following collectability estimates are reasonable and should be used to adjust the allowance for doubtful accounts at 12/31/17: invoice classification estimated % by month of sale uncollectible 12/2017 1% 11/2017 5% 10/2017 10% prior to 10/2017 60%