Question

It takes money 20 years to triple at a certain rate of interest. How long does it take for money to double at this rate?

Answer 1

69.66 years =70 years

Explanation:

Let's calculate the time it takes for the money to double at the given rate of interest.

First, we've previously found that the rate of interest, r, is approximately:

r ≈ 3^(1/20) - 1

Now, let's calculate it:

r ≈ 3^(1/20) - 1 ≈ 0.0494 (rounded to four decimal places)

Now, we can use this value of r in the formula:

t = ln(2) / ln(1 + r)

Plug in the value of r:

t ≈ ln(2) / ln(1 + 0.0494)

Now, calculate it:

t ≈ ln(2) / ln(1.0494) ≈ 69.66 years (rounded to two decimal places)

So, it takes approximately 69.66 years for the money to double at the given rate of interest, which is approximately 4.94%.