The compound interest on ₹20,000 at 5% per annum, compounded annually, is ₹2,050. What is the time period?

compound interest = CI = ₹2,050

principal amount = P = ₹20,000

rate of interest = R = 5%

time period = T

$$CI=P\left[\left(1+\frac{R}{100}\right)^T-1\right]$$

$$2050=20000\left[\left(1+\frac{5}{100}\right)^T-1\right]$$

$$2050=20000\left[\left(1+\frac{1}{20}\right)^T-1\right]$$

$$41=400\left[\left(\frac{21}{20}\right)^T-1\right]$$

$$\frac{41}{400}+1=\left(\frac{21}{20}\right)^T$$

$$\left(\frac{21}{20}\right)^2=(\frac{21}{20})^T$$
T = 2

So the time period is 2 years.