A certain scheme of investment in simple interest declares that it triples the investment in 8 years. If you want to quadruple the money through that scheme for how many years you have to invest for = ?

111 years 6 months
210 years 8 months
310 years
412 years

Answer:- 1

Explanation:-

Solution:

\begin{aligned} P + \frac{P \times r \times t}{100} = 3 P \\ \Rightarrow 1 + \frac{r t}{100} = 3 \\ \Rightarrow \frac{rt}{100} = 2 \\ \Rightarrow r = \frac{2 \times 100}{8} = 25 % \\ so, (1 + \frac{rt}{100}) = 4 \\ \Rightarrow \frac{rt}{100} = 3 \\ \Rightarrow t = \frac{3 \times 100}{25} \\ \Rightarrow t = 12 years \end{aligned}

$\eqalign{ & {\text{P}} + \frac{{P \times {\text{r}} \times {\text{t}}}}{{100}} = 3{\text{P}} \cr & \Rightarrow 1 + \frac{{rt}}{{100}} = 3 \cr & \Rightarrow \frac{{{\text{rt}}}}{{100}} = 2 \cr & \Rightarrow {\text{r}} = \frac{{2 \times 100}}{8} = 25\% \cr & {\text{so, }}\,\left( {1 + \frac{{{\text{rt}}}}{{100}}} \right) = 4 \cr & \Rightarrow \frac{{{\text{rt}}}}{{100}} = 3 \cr & \Rightarrow {\text{t}} = \frac{{3 \times 100}}{{25}} \cr & \Rightarrow {\text{t}} = 12\,{\text{years}} \cr}$