Question

Rajiv Bhardwaj has a recurring deposit account in a bank of Rs 600 per month. If bank pays simple interest of 7% p.a. and he gets Rs 15450 as maturity amount , find the total time for which the account was held.

Answer 1

The amount was deposited for 24 months. Is it correct?

Answer 2

Answer:

The account was held for 2 years.

Simple Interest = $\bold{\mathrm{P} \times \frac{n+(n+1)}{2 \times 12} \times \frac{R}{100}}$

Where P – principal, n – number of years, R – rate of interest

Simple Interest =  $600 \times \frac{n+(n+1)}{24} \times \frac{7}{100}$

$=\frac{7}{4}[n \times(n+1)]$

Amount = P × n + SI

15450 =  $=600 \times n+\frac{7}{4}[n \times(n+1)]$

$\begin{array}{l}{15450=\frac{(600+4 * n)+7[n+(n+1)]}{4}} \\ {61800=2400 n+7 n^{2}+7 n} \\ {61800=2407 n+7 n^{2}} \\ {7 n^{2}+2407 n-61800=0} \\ {7 n^{2}-168 n+2575 n-61800=0}\end{array}$

7n (n – 24) + 2575 (n – 24) = 0

(n – 24)(7n + 2575) = 0

n = 24, = 2 years