Math Problem Statement

Maria has recently inherited $7900, which she wants to deposit into a savings account. She has determined that her two best bets are an account that compounds semi-annually at an annual rate of 5.1% (Account 1) and an account that compounds annually at an annual rate of 4.7% (Account 2).

Step 1 of 2 :  

Which account would pay Maria more interest?

Solution

To determine which account will pay Maria more interest, we will calculate the future value of the inherited $7900 in both accounts after 1 year. We'll use the compound interest formula:

A=P(1+rn)ntA = P \left( 1 + \frac{r}{n} \right)^{nt}

Where:

  • AA is the amount of money accumulated after interest.
  • PP is the principal amount (initial investment) = $7900.
  • rr is the annual interest rate (as a decimal).
  • nn is the number of times the interest is compounded per year.
  • tt is the time the money is invested for (in years).

Account 1 (compounded semi-annually):

  • P=7900P = 7900
  • r=5.1%=0.051r = 5.1\% = 0.051
  • n=2n = 2 (semi-annually)
  • t=1t = 1 year

A1=7900(1+0.0512)21A_1 = 7900 \left( 1 + \frac{0.051}{2} \right)^{2 \cdot 1}

Account 2 (compounded annually):

  • P=7900P = 7900
  • r=4.7%=0.047r = 4.7\% = 0.047
  • n=1n = 1 (annually)
  • t=1t = 1 year

A2=7900(1+0.0471)11A_2 = 7900 \left( 1 + \frac{0.047}{1} \right)^{1 \cdot 1}

Let's calculate the future values for both accounts to determine which one pays more interest.### Future Values:

  • Account 1 (compounded semi-annually): $8308.04
  • Account 2 (compounded annually): $8271.30

Interest Earned:

  • Account 1: $408.04
  • Account 2: $371.30

Thus, Account 1 pays Maria more interest, with a difference of approximately $36.74.

Would you like to see more details on this calculation, or do you have any questions?

Here are 5 related questions you might find useful:

  1. What happens if Maria deposits her money for 5 years?
  2. How does monthly compounding compare to semi-annual compounding?
  3. What if Maria deposits an additional $1000 after 6 months?
  4. How would a different initial amount (e.g., $5000) affect the interest earned?
  5. What is the formula for continuous compounding, and how would it compare?

Tip: Compounding more frequently generally results in more interest earned.

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Math Problem Analysis

Mathematical Concepts

Compound Interest
Exponential Growth

Formulas

Compound Interest Formula: A = P(1 + r/n)^(nt)

Theorems

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Suitable Grade Level

Grades 10-12