Find the sum on which the compound interest for 3 years at 10% per annum amounts to ₹ 1655.

Let sum of money be ₹ x.

Given,

n = 3 years

r = 10%

C.I. = ₹ 1655

A = P + I = ₹ x + ₹ 1655

By formula,

A = $P\Big(1 + \dfrac{r}{100}\Big)^n$

Substituting values we get :

$\Rightarrow x + 1655 = x \times \Big(1 + \dfrac{10}{100}\Big)^3 \\[1em] \Rightarrow x + 1655 = x \times \Big(\dfrac{110}{100}\Big)^3 \\[1em] \Rightarrow x + 1655 = x \times \Big(\dfrac{11}{10}\Big)^3 \\[1em] \Rightarrow x + 1655 = x \times \dfrac{1331}{1000} \\[1em] \Rightarrow 1000(x + 1655) = 1331x \\[1em] \Rightarrow 1000x + 1655000 = 1331x \\[1em] \Rightarrow 1331x - 1000x = 1655000 \\[1em] \Rightarrow 331x = 1655000 \\[1em] \Rightarrow x = \dfrac{1655000}{331} \\[1em] \Rightarrow x = ₹5000.$

Hence, sum of money = ₹ 5000.