Mr. Britto deposits a certain sum of money each month in a Recurring Deposit Account of a bank. If the rate of interest is of 8% per annum and Mr. Britto gets ₹ 8088 from the bank after 3 years, find the value of his monthly instalment.

Let Mr. Britto deposit ₹ x per month.

So,

P = ₹ x, n = (3 × 12) = 36 months and r = 8%

I = $P \times \dfrac{n(n + 1)}{2 \times 12} \times \dfrac{r}{100}$

$\therefore I = ₹ x \times \dfrac{36 \times 37}{2 \times 12} \times \dfrac{8}{100} \\[1em] = ₹ \dfrac{111x}{25}$

Maturity value = Sum deposited + Interest

$= ₹ x \times 36 + ₹\dfrac{111x}{25} \\[1em] = ₹\dfrac{900x + 111x}{25} \\[1em] = ₹\dfrac{1011x}{25}$

Given, maturity value = ₹ 8088.

$\therefore \dfrac{1011x}{25} = 8088 \\[1em] \Rightarrow x = \dfrac{8088 \times 25}{1011} \\[1em] \Rightarrow x = ₹ 200.$

Hence, Mr. Britto paid ₹ 200 per month.