Question 1097227: The annual interest rate on a credit card is 12.99%.if the minimum of $20 is made each month , how many months will it take to pay off an unpaid balance of $910.61? Assume that no purchases are made with the credit card.
Answer by jorel1380(3719)   (Show Source):
You can put this solution on YOUR website! Let the monthly interest rate be r and the principal be p, the
monthly payment be x, and n be the number of months to pay the debt off. Then p = x*(1 - (1+r)^-n)/r is the formula you need in order to determine the number of months you need. In this case, the monthly interest rate is 12.99%/12, or 0.010825. So:
910.61=20*(1-(1+0.010825)^-n)/0.010825
0.4928676625=1-(1.010815)^-n
1.010815^-n=0.5071323375
ln 1.010815^-n=ln 0.5071323375
-n ln 1.010815=ln 0.5071323375
n=63.12 months
☺☺☺☺
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