At what percentage of simple interest does an amount of money double in 12 years?

Correct option is C

Let's solve this using the formula for Simple Interest:

​$$\text{Simple Interest} = \frac{\text{Principal} \times \text{Rate} \times \text{Time}}{100}$$​​

Given that the amount doubles, the Simple Interest (SI) will be equal to the Principal (P):

​$$P = \frac{P \times R \times 12}{100}$$​​

Cancel P from both sides:

​$$1 = \frac{R \times 12}{100}$$​​

Solving for R:

​$$R = \frac{100}{12} \approx 8.33$$​​

So, the required simple interest rate to double the money in 12 years is 8.33% per annum., which is equal to Option C) 8 $$\frac{1}{3}$$​​