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Suppose $4,000 is invested at 8% interest compounded continuously. How long will it take for the investment to grow to $8,000? Use the model A ( T ) = P e^rt and round to the nearest tenth of a year.

It will take approximately ____ years for the investment to grow to $8,000.

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Final answer:

To find out how long it will take for $4,000 to grow to $8,000 with 8% interest compounded continuously, we use the formula A(T) = Pert. Solving the equation 8,000 = 4,000e0.08T gives T ≈ 8.66, which means it will take approximately 8.7 years.

Step-by-step explanation:

To determine how long it will take for an investment of $4,000 at 8% interest compounded continuously to grow to $8,000, we can use the continuous compounding formula A(T) = Pert. Here, A(T) represents the amount of money accumulated after time T, P is the principal amount, e is the base of the natural logarithm, r is the rate of interest, and T is the time in years.

According to the given problem:

  • Final amount A(T) = $8,000
  • Principal P = $4,000
  • Rate r = 8% or 0.08

We can set up the equation 8,000 = 4,000e0.08T and solve for T.

First, divide both sides by 4,000 to get e0.08T = 2. Next, take the natural logarithm of both sides to get 0.08T = ln(2). Finally, divide by 0.08 to solve for T.

The calculation is as follows:

  1. e0.08T = 2
  2. 0.08T = ln(2)
  3. T = ln(2) / 0.08
  4. T ≈ 8.66

Therefore, it will take approximately 8.7 years for the investment to grow to $8,000.

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