问答题   The balance on the receivable account at 1 October is $4,000. The total of the sales day book for October is $1,600. The cash receipts book contains total receipts from customers of $3,500 included in the total receipts was $1,000 received from cash sales. It also contains a contra to the payable ledger of $400. The remainder of the receipts were from credit customers.
    What should be the balance on the receivable account at 31 October? ______