A certain sum doubles in 7 years at simple interest. The same sum under the same interest rate will become 4 times in how many years = ?

114 years
228 years
321 years
410 years

Answer:- 1

Explanation:-

Solution:

\begin{aligned} \frac{(n - 1)}{t_{1}} = \frac{(m - 1)}{t_{2}} \\ \frac{1}{7} = \frac{3}{t_{2}} \\ t_{2} = 21 years \end{aligned}

$\eqalign{ & \frac{{\left( {n - 1} \right)}}{{{t_1}}} = \frac{{\left( {m - 1} \right)}}{{{t_2}}} \cr & \frac{1}{7} = \frac{3}{{{t_2}}} \cr & {t_2} = 21{\text{ years}} \cr}$

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", "dateCreated": "7/24/2019 10:09:12 AM", "author": { "@type": "Person", "name": "Nitin Sir" } }, "suggestedAnswer": { "@type": "Answer", "text": "

Solution:

\begin{aligned} \frac{(n - 1)}{t_{1}} = \frac{(m - 1)}{t_{2}} \\ \frac{1}{7} = \frac{3}{t_{2}} \\ t_{2} = 21 years \end{aligned}

$\eqalign{ & \frac{{\left( {n - 1} \right)}}{{{t_1}}} = \frac{{\left( {m - 1} \right)}}{{{t_2}}} \cr & \frac{1}{7} = \frac{3}{{{t_2}}} \cr & {t_2} = 21{\text{ years}} \cr}$ ", "dateCreated": "7/24/2019 10:09:12 AM" } }