Which of the following statements is true regarding aging accounts receivable? 1) The aging of accounts receivable involves applying lower uncollectible percentage estimates to older receivables. 2) All of the statements are true. 3) The aging method of estimating uncollectible accounts is based on the assumption that the longer an account receivable remains outstanding, the less likely it is to be collected. 4) An aging schedule is used to improve the estimate used in the percent of revenue method of determining the uncollectible accounts expense.