Question

question 5 of 10
ahmad just put some money into a cd that pays 11.3% interest. according to
the rule of 72, in approximately how many years will he have 4 times the
amount of money that he has now?

a. 12.7 years

b. 19.1 years

c. 6.4 years

d. 25.5 years

Explanation:

Step1: Find doubling time via Rule of 72

The Rule of 72 formula for doubling time is $\text{Time to double} = \frac{72}{\text{Interest Rate}}$.
Substitute the rate: $\text{Time to double} = \frac{72}{11.3} \approx 6.37$ years.

Step2: Calculate time to quadruple

To get 4x the original amount, the money must double twice.
$\text{Total Time} = 2 \times 6.37 \approx 12.7$ years.

Answer:

A. 12.7 years