Hi Jenna,
If I am understanding the question correctly, the 3.1% is an annual rate then you can calculate this a couple of ways. You can break it down to a daily interest rate ( 3.1% /365) and calculate as follows Balance x Daily Interest Rate x Days = Total
Balance Daily Int. Days Total
$12,500.00 $1.08 12 $12.92
$8,700.00 $0.75 9 $6.74
$9,980.00 $0.86 9 $7.73
$27.39
Or you can find the average daily balance and multiply by monthly rate as seen below.
Balance Days Total
$ 12,500.00 12 $ 150,000.00
$ 8,700.00 9 $ 78,300.00
$ 9,980.00 9 $ 89,820.00
$ 318,120.00
Average Daily Balance $ 10,604.00
Monthly Rate 0.258%
Interest $ 27.39
