Question

4.
Find the rate of compound interest per annum at
which Rs 12,500 will amount to Rs 15,680 in 2
years.​

Answer 1

$\boxed{\texttt{\fcolorbox{Red}{aqua}{Hey Mate}}}$

Here is your answer

P = Rs 12500

A = Rs 15680

R = r % let

T = 2 years , n = 2

As we know the formula

A = P (1+r/100)^n

$\begin{gathered}15680 = 12500 \times (1 + \frac{r}{100} ) {}^{2} \\ \frac{15680}{12500} = ( \frac{100 + r}{100} ) {}^{2} \\ \frac{784}{625} = ( \frac{100 + r}{100} ) {}^{2} \\ ( \frac{28}{25} ) {}^{2} = ( \frac{100 + r}{100} ) {}^{2} \\ \frac{28}{25} = \frac{100 + r}{100} \\ 28 \times 100 = 25 \times 100 + 25r \\ 25r = 2800 - 2500 \\ 25r = 300 \\ r \frac{300}{25} \\ r = 12\%\end{gathered}$

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Answer 2

$\huge\boxed{\underline{\sf{\red{a}\green{n}\pink{s}\orange{w}\blue{e}\pink{r}}}}$

Here is your answer

P = Rs 12500

A = Rs 15680

R = r % let

T = 2 years , n = 2

As we know the formula

A = P (1+r/100)^n

$\begin{gathered}\begin{gathered}15680 = 12500 \times (1 + \frac{r}{100} ) {}^{2} \\ \frac{15680}{12500} = ( \frac{100 + r}{100} ) {}^{2} \\ \frac{784}{625} = ( \frac{100 + r}{100} ) {}^{2} \\ ( \frac{28}{25} ) {}^{2} = ( \frac{100 + r}{100} ) {}^{2} \\ \frac{28}{25} = \frac{100 + r}{100} \\ 28 \times 100 = 25 \times 100 + 25r \\ 25r = 2800 - 2500 \\ 25r = 300 \\ r \frac{300}{25} \\ r = 12\%\end{gathered} \end{gathered}$