Joan borrowed

$15,000.00

to buy a car. She repaid

$4000.00

four

months later and

$6800.00

eight

months later. After twelve months, she borrowed an additional

$4800.00,

and repaid

$4400.00

after

19

months. She paid the entire balance, including the interest, after 24 months. Interest was

6%

compounded monthly for the first year and

5.5%

compounded monthly for the remaining time. What was the size of the final payment?