Question

At what time will a sum of 3000 will amount to 3993 at 10% p.a compounded
annually?​

Answer 1

Answer:

At what percent per annum will Rs. 3000/- amounts to Rs. 3993/- in 3 years if the interest is compounded annually?

[A]13%

[B]10%

[C]9%

[D]11%

10%

P = Rs. 3000 , A = Rs. 3993 , n = 3 years

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

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

=>\left ( 1+\frac{r}{100} \right )^{3} = \frac{3993}{3000} = \frac{1331}{1000}

=>\left ( 1+\frac{r}{100} \right )^{3} = \left ( \frac{11}{10} \right )^{3}

=>1+\frac{r}{100} = \frac{11}{10}

=>\frac{r}{100} = \frac{11}{10}-1

=> \frac{r}{100} = \frac{1}{10}

=> r = \frac{100}{10} = 10\%

Hence option [B] is the right ansewr.