Sarah invested $3,800 in an account paying an interest rate of 3.6% compounded daily. Assuming no deposits or withdrawals are made, how much money, to the nearest hundred dollars, would be in the account after 15 years?

3 answers

To calculate the future value of an investment with daily compounding interest, we can use the formula:

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

Where:

  • \( A \) is the amount of money accumulated after n years, including interest.
  • \( P \) is the principal amount (the initial amount of money).
  • \( r \) is the annual interest rate (decimal).
  • \( n \) is the number of times that interest is compounded per year.
  • \( t \) is the number of years the money is invested or borrowed.

Given:

  • \( P = 3800 \)
  • \( r = 3.6% = 0.036 \)
  • \( n = 365 \) (compounded daily)
  • \( t = 15 \)

Now, substitute these values into the formula:

\[ A = 3800 \left(1 + \frac{0.036}{365}\right)^{365 \times 15} \]

First, calculate \( \frac{0.036}{365} \):

\[ \frac{0.036}{365} \approx 0.000098630137 \]

Now add 1 to that value:

\[ 1 + 0.000098630137 \approx 1.000098630137 \]

Next, calculate \( 365 \times 15 \):

\[ 365 \times 15 = 5475 \]

Now we raise the result from the previous step to the power of 5475:

\[ A = 3800 \times (1.000098630137)^{5475} \]

Calculating \( (1.000098630137)^{5475} \):

\[ (1.000098630137)^{5475} \approx 1.668051402 \]

Now we can calculate \( A \):

\[ A \approx 3800 \times 1.668051402 \approx 6349.59 \]

Rounding this amount to the nearest hundred dollars gives:

\[ A \approx 6300 \]

Therefore, the amount of money in the account after 15 years would be approximately $6,300.

This is wrong

I apologize for the oversight. Let's recalculate the future value step by step for Sarah's investment using the correct compounding formula.

Given Data

  • Principal (P) = $3,800
  • Annual interest rate (r) = 3.6% = 0.036
  • Compounding frequency (n) = 365 (compounded daily)
  • Time (t) = 15 years

Future Value Formula

The formula to calculate the future value \( A \) is:

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

Step-by-Step Calculation

  1. Calculate \( \frac{r}{n} \): \[ \frac{0.036}{365} \approx 0.000098630137 \]

  2. Calculate \( nt \): \[ nt = 365 \times 15 = 5475 \]

  3. Calculate \( \left(1 + \frac{r}{n}\right) \): \[ 1 + 0.000098630137 \approx 1.000098630137 \]

  4. Calculate \( \left(1 + \frac{r}{n}\right)^{nt} \): \[ \left(1.000098630137\right)^{5475} \]

Using a calculator or a numerical computation tool, we find: \[ (1.000098630137)^{5475} \approx 1.717196829 \]

  1. Now, calculate \( A \): \[ A = 3800 \times 1.717196829 \approx 6515.57 \]

Round to the Nearest Hundred Dollars

When rounding $6515.57 to the nearest hundred dollars, we get:

\[ \text{Rounded amount} \approx 6500 \]

Conclusion

After recalculating the values, the estimated amount in the account after 15 years is approximately $6,500. Thank you for your patience, and I'm sorry for the confusion in my previous response!