Question

in how many years will a sum of money triple itself at the rate of 20% per annum simple intrest ?

Answer 1

$\mathfrak{Answer:}$

= 10 years .

$\mathfrak{Step-by-Step\;Explanation:}$

$\underline{\bold{Given\;in\;the\;Question:}}$

• A sum becomes 3 times.
• Rate = 20% p.a.

$\mathbb{SOLUTION:}$

Let the principle be Rs. x.

So amount = Rs. 3x.

$\bigstar\quad\textsf{We know that : \boxed{\bold{Simple\;Interest=Amount-Principle.}}}\\\\\\\tt{=3x-x}\\\\\\\tt{=Rs.2x.}$

$\bold{Also:}\\\\\\\boxed{\bold{SI=\dfrac{Principle\times Time\times Rate}{100}}}\\\\\\\mathfrak{According\;to\;Question:}\\\\\\\implies\tt{2x=\dfrac{x\times t\times 20}{100}}\\\\\\\implies\tt{200x=20xt}\\\\\\\implies\tt{t=\dfrac{200x}{20x}}\\\\\\\implies\tt{t=10\;years.}\\\\\\\\\boxed{\boxed{\bold{Time=10\;years}}}$

Answer 2

$\sf\underline{Step-by-step \: explanation}$

Let the principal be x then the amount will be 3x

R = 20 %

A = 3x

P = x

S.I = 2x [S.I. = A - P = 3x - x = 2x]

T = T

Method,

T =

$\tt\dfrac{si \: \times \: 100}{p \: \times \: r}$

Solving,

T =

$\tt\dfrac{2x \: \times \: 100}{20 \: \times \: x }$

T =

$\tt\dfrac{200x}{20x}$

After Cancellation...

10 years.

Hence the time taken will be 10 years