In: Math
The annual interest rate on a credit card is 18% with interest compounded monthly. If a payment of $100 is made at the end of each month, how many months will it take to pay off an unpaid balance of $2,583.56 (assuming no additional purchases are made)?
Future value of annuity for periodic payments at the end of each month is
where P=Periodic Payment, r=Rate of Interest and FV=Future Value
Given,
Unpaid amount is 2583.56 implies FV=2583.56
Rate of interest per annum is 18% implies r=0.18. For monthly compounding, r=(0.18/12)=0.015
Period Payment is 100 implies P=100
Therefore,
That is
Therefore,
Hence, it will take 22 months to pay off the unpaid balance