The Continental Bank made a loan of $21,000.00 on March 4 to Dr. Hirsch to purchase equipment for her office. The loan was secured by a demand loan subject to a variable rate of interest that was 8% on March 4 . The rate of interest was raised to 8.4% effective July 1 and to 8.9% effective September 1 . Dr. Hirsch made partial payments on the loan as follows: $700 on May 4;$1000 on June 29; and $400 on October 18 . Each payment is first applied to any accumulated interest. Any much must Dr. Hirsch pay on October 31? Dr. Hirsch must pay { on October 31 . (Round the final answer to the nearest cent as needed. Round all intermediate values to six decimal places as needed.)