Math Problem Statement

Bridget opened a savings account and deposited $800.00 as principal. The account earns 7% interest, compounded continuously. What is the balance after 2 years? Use the formula A=Pert, where A is the balance (final amount), P is the principal (starting amount), e is the base of natural logarithms (≈2.71828), r is the interest rate expressed as a decimal, and t is the time in years. Round your answer to the nearest cent.

Solution

To find the balance after 2 years, we can use the formula for continuous compounding:

A=PertA = P e^{rt}

where:

  • P=800P = 800 (the principal),
  • r=0.07r = 0.07 (the interest rate as a decimal),
  • t=2t = 2 (the time in years),
  • e2.71828e \approx 2.71828.

Step-by-Step Solution

  1. Substitute the values into the formula: A=800×e(0.07×2)A = 800 \times e^{(0.07 \times 2)}

  2. Calculate the exponent 0.07×2=0.140.07 \times 2 = 0.14, so the equation becomes: A=800×e0.14A = 800 \times e^{0.14}

  3. Calculate e0.14e^{0.14}: Using the approximate value, e0.141.15027e^{0.14} \approx 1.15027.

  4. Multiply by the principal: A=800×1.15027920.22A = 800 \times 1.15027 \approx 920.22

Final Answer

The balance after 2 years, rounded to the nearest cent, is $920.22.

Would you like more details on continuous compounding, or have any questions?


  1. What would be the balance after 3 years instead of 2?
  2. How does continuous compounding compare to annual compounding at the same rate?
  3. What if the interest rate were 8% instead of 7%?
  4. How would a one-time additional deposit affect the balance in continuous compounding?
  5. How does the formula for continuous compounding relate to other compound interest formulas?

Tip: Continuous compounding is particularly powerful as it applies the interest constantly, yielding slightly higher results than daily, monthly, or annual compounding at the same rate.

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Math Problem Analysis

Mathematical Concepts

Exponential Growth
Continuous Compounding
Interest Calculation

Formulas

A = P * e^(rt)

Theorems

Properties of Exponential Functions

Suitable Grade Level

Grades 10-12