Manny invests $100 in an account that is compounded continuously at an annual interest rate of 2%, according to the formula A=Pert

, where A
is the amount accrued, P
is the principal, r is the rate of interest, and t is the time, in years. In 20 years, how much will Manny’s investment be worth to the nearest dollar?

1 answer

To find out how much Manny's investment will be worth after 20 years with continuous compounding, we can use the formula:

\[ A = Pe^{rt} \]

Where:

  • \( A \) is the amount accrued (future value).
  • \( P \) is the principal amount (initial investment).
  • \( r \) is the annual interest rate (in decimal).
  • \( t \) is the time in years.
  • \( e \) is the base of the natural logarithm, approximately equal to 2.71828.

In this case:

  • \( P = 100 \) (the initial investment)
  • \( r = 0.02 \) (2% as a decimal)
  • \( t = 20 \) (the number of years)

Now we can plug in the values:

\[ A = 100 e^{0.02 \times 20} \] \[ A = 100 e^{0.4} \]

Next, we need to calculate \( e^{0.4} \). Using a calculator:

\[ e^{0.4} \approx 1.49182 \]

Now we can calculate \( A \):

\[ A = 100 \times 1.49182 \approx 149.182 \]

Finally, rounding to the nearest dollar:

\[ A \approx 149 \]

Thus, after 20 years, Manny’s investment will be worth approximately $149.