At an effective interest rate of 12%, a single sum invested today will double itself in approximately:
A) 8 years.
B) 12 years.
C) 6 years.
D) insufficient data to determine answer.

Question

Quizplus · Accepted Answer

Using the rule of 72, we can estimate how long it will take for an investment to double by dividing 72 by the annual interest rate. 
So, 72/12 = 6, which means the investment will double in approximately 6 years. Therefore, the best choice is C.

At an Effective Interest Rate of 12%, a Single Sum