A certain sum of money amounts to Rs. 1331 in 3 years at 10 percent compounded annually. Find the sum invested.

Correct option is B

Given:
Amount in 3 years = Rs 1331
Formula Used:
​$$\text{Amount} = P \times \left(1 + \frac{r}{100} \right)^n$$​​
P → principal; r → rate of interest; n → number of years
Solution:
​$$1331 = P \times \left(1 + \frac{10}{100}\right)^3\\1331 = P \times \left(\frac{110}{100}\right)^3 \\\Rightarrow 1331 = P \times \left(\frac{11}{10}\right)^3 \\\Rightarrow 1331 = P \times \frac{1331}{1000} \\\ \\\Rightarrow P = \frac{1331 \times 1000}{1331} = 1000 \\$$​​