College

Felipe transferred a balance of [tex]$\$3700$[/tex] to a new credit card at the beginning of the year. The card offered an introductory APR of [tex]$5.9\%$[/tex] for the first 4 months and a standard APR of [tex]$17.2\%$[/tex] thereafter. If the card compounds interest monthly, which of these expressions represents Felipe's balance at the end of the year? (Assume that Felipe will make no payments or new purchases during the year, and ignore any possible late payment fees.)

A. [tex]$3700\left(1+\frac{0.059}{4}\right)^{12}\left(1+\frac{0.172}{8}\right)^{12}$[/tex]

B. [tex]$3700\left(1+\frac{0.059}{12}\right)^{12}\left(1+\frac{0.172}{12}\right)^{12}$[/tex]

C. [tex]$3700\left(1+\frac{0.059}{4}\right)^4\left(1+\frac{0.172}{8}\right)^8$[/tex]

D. [tex]$3700\left(1+\frac{0.059}{12}\right)^4\left(1+\frac{0.172}{12}\right)^8$[/tex]

Answer :

Sure, let's break down the solution step-by-step:

Felipe transferred a balance of [tex]$3,700 to a new credit card at the beginning of the year. The card offers an introductory APR (Annual Percentage Rate) of 5.9% for the first 4 months, and a standard APR of 17.2% for the remaining months of the year. The interest compounds monthly.

Here’s how we can calculate Felipe’s balance at the end of the year:

1. Introductory Period (4 months):
- The introductory APR is 5.9%, which is applied for the first 4 months.
- Since the interest compounds monthly, we convert the annual rate to a monthly rate: \( \frac{0.059}{12} \).
- The balance growth factor for the 4 months is \((1 + \frac{0.059}{12})^4\).

2. Standard Period (8 months):
- After the introductory period, the standard APR of 17.2% applies.
- Convert the annual rate to a monthly rate: \( \frac{0.172}{12} \).
- The balance growth factor for the 8 months is \((1 + \frac{0.172}{12})^8\).

3. Calculating the Final Balance:
- Start with the initial balance of $[/tex]3,700.
- Multiply by the growth factor for the introductory period to account for the interest accrued during the first 4 months.
- Then, multiply by the growth factor for the standard period to account for the interest during the remaining 8 months.

The expression for the final balance at the end of the year is:
[tex]\[
(\$ 3700) \times \left(1 + \frac{0.059}{12}\right)^4 \times \left(1 + \frac{0.172}{12}\right)^8
\][/tex]

This matches option D in the provided choices. Therefore, the correct expression representing Felipe's balance at the end of the year is:

D. [tex]\((\$ 3700)\left(1+\frac{0.059}{12}\right)^4\left(1+\frac{0.172}{12}\right)^8\)[/tex]