Question

At what rate percent compound interest does a sum of money becomes four-fold in 2 years.

Answer 1

Answer:

r = 200\%

Step-by-step explanation:

Let Principal (P) = Rs x,

Amount (A) = Rs 9x (given)

Number of times interest paid (n) = 2

Let Rate of interest = r,

$\boxed {A= P\left(1+\frac{r}{100}\right)^{n}}$

$\implies 9x = x\left(1+\frac{r}{100}\right)^{2}$

$\implies 9 = \left(1+\frac{r}{100}\right)^{2}$

$\implies \sqrt{9} = \left(1+\frac{r}{100}\right)</p><p>$

$\implies 3-1= \frac{r}{100}$

$\implies 2= \frac{r}{100}$

$\implies 2\times 100=r$

$\implies r = 200\%$

Therefore,

r = 200\%

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Answer 2

Answer:

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