Summit Industries has a past history of uncollectible accounts, as shown below. Estimate the allowance for doubtful accounts, based on the aging of receivables schedule you completed in Exercise 9-8.

                                                     Percent

Age Class                              Uncollectible

Not past due                                        1%

1–30 days past due                              6

31–60 days past due                           20

61–90 days past due                           35

Over 90 days past due                        50