Kamal invested ₹5,500 at compound interest at the rate of R% per annum for 3 years. If the interest received by Kamal after 3 years is equal to 33.1% of the amount invested, then find the value of R.

Formulae for the compound interest is $$p\cdot\left(1+\frac{r}{100}\right)^n$$

Here n=3, p=5500. The amount he receives after three is equal to $$5500\cdot\left(1+\frac{10}{100}\right)^3$$

It is given that he receives an interest of 33.1% after three years. So, the total sum would be 133.1% of the initial investment.

$$5500\cdot\left(1+\frac{10}{100}\right)^3=5500\cdot\frac{133.1}{100}$$

$$\left(1+\frac{r}{100}\right)^3=1.331$$

$$\left(1+\frac{r}{100}\right)^3=\left(1.1\right)^3$$

From this, r=10.