Problem 6-4 Sigma Company began operations on January 1, 20x0. The Sigma Company calculates its allowance for doubtful accounts by aging the accounts receivable based on the following percentages: Days Past Invoice Date 0 - 30 31 - 60 61 - 90 Over 90 Percent Estimated To be Uncollectible 1% 5% 20% 80% The following additional information relates to the years ended December 31, 20xl and 20x0: 20x1 20x0 Credit Sales Collections (excluding recoveries) Accounts written off Recovery of accounts previously written off $3,000,000 2,915,000 27,000 7,000 $2,800,000 2,400,000 16,000 Days Past Invoice at December 31 - 0 - 30 31 - 60 61 - 90 Over 90 277,000 80,000 60,000 25,000 234,000 90,000 45,000 15,000 Required Prepare all journal entries to record the above transactions