Dirk Ward borrowed $12,000.00 for investment purposes on May 24 on a demand note providing for a variable rate of interest and payment of any accrued interest on December 31. He paid $900 on June 6, $200 on September 14, and $1200 on November 10. How much is the accrued interest on December 31 if the rate of interest was 7% on May 24, 7.4% effective August 1, and 7.8% effective November 1?