At which rate of simple interest does an amount become double in 12 years?

Given,

Time (T) = 12 years

Let the Principal amount = P

Rate of Simple Interest = R

According to the Problem,

Amount = 2P

$$=$$>  Principal + Simple Interest = 2P

$$=$$>  P + $$\frac{\text{P}\times\text{T}\times \text{R}}{100}$$ = 2P

$$=$$>  $$\frac{\text{P}\times12\times \text{R}}{100}$$ = 2P - P

$$=$$>  $$\frac{\text{P}\times12\times \text{R}}{100}$$ = P

$$=$$>  $$\text{R}=\frac{100}{12}$$

$$=$$>  $$\text{R}=8\frac{1}{3}$$%

Hence, the correct answer is Option D