Math Problem Statement

In 1885​, a person sold a house to a lady for ​$26. If the lady had put the ​$26 into a bank account paying 6​% ​interest, how much would the investment have been worth in the year 2010 if interest were compounded in the following​ ways? a. monthly                 b. continuously Question content area bottom Part 1 a. If compounded​ monthly, the investment would be worth ​$    46,139 in 2010. ​(Round to the nearest dollar as​ needed.) Part 2 b. If compounded​ continuously, the investment would be worth ​$    enter your response here in 2010. ​(Round to the nearest dollar as​ needed.)

Solution

To solve this problem, we'll use two different compound interest formulas based on the type of compounding (monthly and continuously). We are given:

  • Principal (P) = $26
  • Annual interest rate (r) = 6% or 0.06
  • Time (t) = 2010 - 1885 = 125 years

Part 1: Monthly Compounding

The formula for monthly compounding is: 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 ($26).
  • rr is the annual interest rate (0.06).
  • nn is the number of times interest is compounded per year (12 for monthly).
  • tt is the time the money is invested for (125 years).

Substituting the given values:

A=26(1+0.0612)12×125A = 26 \left(1 + \frac{0.06}{12}\right)^{12 \times 125} Now, let’s calculate it:

A=26(1+0.005)1500A = 26 \left(1 + 0.005\right)^{1500} A=26×(1.005)1500A = 26 \times (1.005)^{1500}

Using a calculator, we get:

A46,139A \approx 46,139

So, the investment would be worth $46,139 if compounded monthly.

Part 2: Continuous Compounding

The formula for continuous compounding is: A=PertA = P \cdot e^{rt} Where:

  • AA is the amount of money accumulated after interest.
  • PP is the principal amount ($26).
  • rr is the annual interest rate (0.06).
  • tt is the time the money is invested for (125 years).
  • ee is the base of the natural logarithm (approximately 2.71828).

Substituting the values:

A=26e0.06×125A = 26 \cdot e^{0.06 \times 125} A=26e7.5A = 26 \cdot e^{7.5}

Using a calculator:

A26×1,823.293A \approx 26 \times 1,823.293 A47,466A \approx 47,466

So, the investment would be worth approximately $47,466 if compounded continuously.


Final Answers:

  • a. Monthly compounding: The investment would be worth $46,139.
  • b. Continuous compounding: The investment would be worth $47,466.

Would you like further details or clarifications? Here are some related questions you might find interesting:

  1. What would the investment be worth if the interest rate was 5% instead of 6%?
  2. How would the compounding frequency affect the total amount if the investment was for only 50 years instead of 125?
  3. What is the effect of increasing the compounding frequency (quarterly, daily, etc.) on the total accumulated value?
  4. How would this investment look if the initial amount was $1000 instead of $26?
  5. What are some real-world examples of continuously compounded interest?

Tip: When calculating continuous compounding, remember the key formula involves the natural exponential function ee, which represents continuous growth.

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Math Problem Analysis

Mathematical Concepts

Compound Interest
Exponential Growth

Formulas

A = P(1 + r/n)^(nt) for monthly compounding
A = P * e^(rt) for continuous compounding

Theorems

Compound Interest Theorem
Continuous Compound Interest Theorem

Suitable Grade Level

Grades 10-12