Math Problem Statement

A deposit of $2,300 is made into each of two bank accounts. No additional deposits or withdrawals will be made for 5 years.

Account I earns 2.5% annual simple interest. Account II earns 2.5% interest compounded annually.

Which amount is closest to the difference between the balances of the two accounts at the end of 5 years? A.$287.50 B.$302.24 C.$14.74 D.$147.40

Solution

To solve this problem, we need to calculate the final balances for each account after 5 years, then find the difference between the two balances.

Account I: Simple Interest

Simple interest formula: A=P(1+rt)A = P(1 + rt) Where:

  • P=2300P = 2300 (principal)
  • r=2.5%=0.025r = 2.5\% = 0.025 (interest rate)
  • t=5t = 5 years

A1=2300×(1+0.025×5)=2300×(1+0.125)=2300×1.125=2587.50A_1 = 2300 \times (1 + 0.025 \times 5) = 2300 \times (1 + 0.125) = 2300 \times 1.125 = 2587.50

Account II: Compound Interest

Compound interest formula: A=P(1+r)tA = P(1 + r)^t Where:

  • P=2300P = 2300 (principal)
  • r=0.025r = 0.025 (annual interest rate)
  • t=5t = 5 years

A2=2300×(1+0.025)5=2300×(1.025)5A_2 = 2300 \times (1 + 0.025)^5 = 2300 \times (1.025)^5

Let's calculate (1.025)5(1.025)^5:

A2=2300×1.1314=2602.24A_2 = 2300 \times 1.1314 = 2602.24

Difference between the two accounts:

Difference=A2A1=2602.242587.50=14.74\text{Difference} = A_2 - A_1 = 2602.24 - 2587.50 = 14.74

Thus, the closest answer is: C.14.74\boxed{C. 14.74}

Would you like more details, or do you have any questions?

Here are 5 related questions for practice:

  1. What is the future value of an account earning 3% annual simple interest after 4 years with a deposit of $1,500?
  2. How does compound interest differ from simple interest over longer periods?
  3. What would be the balance if Account II had monthly compounding instead of annual compounding?
  4. How would the difference change if the interest rate was 5% instead of 2.5% for both accounts?
  5. What is the compound interest earned on a $2,000 deposit after 3 years at 4% interest compounded annually?

Tip: Compound interest grows faster than simple interest over time because it earns interest on both the initial principal and previously earned interest!

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Math Problem Analysis

Mathematical Concepts

Interest Calculation
Simple Interest
Compound Interest
Exponential Growth

Formulas

Simple Interest: A = P(1 + rt)
Compound Interest: A = P(1 + r)^t

Theorems

Interest Growth Theorem
Exponential Function

Suitable Grade Level

Grades 10-12