Use PMT (r/n) /[1-(1+r/n) ^-n t to determine the regular payment amount, rounded to the nearest dollar. Your credit card has a balance of $1500 and an annual interest rate of 18 %. You decide to pay off the balance over 2 years.

If there are no further purchases charged to the card, how much must you pay each month (round to nearest dollar)?

1 answer

To calculate the regular monthly payment for paying off your credit card balance of $1500 over 2 years with an annual interest rate of 18%, we can use the formula for the payment on an amortizing loan:

\[ PMT = \frac{(r/n) \cdot P}{1 - (1 + r/n)^{-n \cdot t}} \]

Where:

  • \( P \) is the principal amount (i.e., the balance of the loan, which is $1500).
  • \( r \) is the annual interest rate (as a decimal, so 18% becomes 0.18).
  • \( n \) is the number of payments per year (since payments are monthly, \( n = 12 \)).
  • \( t \) is the number of years (in this case, 2 years).

Now we can plug in the values:

  1. Calculate the interest rate per month: \[ \frac{r}{n} = \frac{0.18}{12} = 0.015 \]

  2. Calculate the total number of payments: \[ n \cdot t = 12 \cdot 2 = 24 \]

Now substitute these values into the PMT formula:

\[ PMT = \frac{(0.015) \cdot 1500}{1 - (1 + 0.015)^{-24}} \]

Calculating the denominator:

  1. Calculate \( (1 + 0.015)^{-24} \): \[ (1 + 0.015)^{-24} = (1.015)^{-24} \approx 0.644 \]

  2. Substitute it back to the equation to find the denominator: \[ 1 - (1.015)^{-24} \approx 1 - 0.644 \approx 0.356 \]

Now, calculate PMT:

\[ PMT = \frac{(0.015) \cdot 1500}{0.356} \]

Calculating the numerator:

\[ (0.015) \cdot 1500 = 22.5 \]

Finally,

\[ PMT = \frac{22.5}{0.356} \approx 63.19 \]

Rounding to the nearest dollar:

\[ PMT \approx 63 \]

Therefore, the monthly payment amount required to pay off the credit card balance over 2 years is $63.