John borrowed some amount of money from a bank at the rate of 10% per annum on compound interest for which interest is compounded annually. If he repaid his loan by paying Rs. 21,961.50 at the end of 4 years, what is the amount he borrowed?

Correct option is B

​​Given:
Rate of interest = 10%
At the end of four years amount paid by him = ₹21,961.50
Concept Used:
A = $$P × (1 + \frac{R}{100})^T$$​​
Where,
A → Amount
P → Principal
R → Rate of interest
T → Time
Solution:
$$21961.50 = P (1+\frac{10}{100})^4\\21961.50 = P (\frac{11}{10})^4\\P = Rs. 15000$$​

Alternate Solution:

Rate = 10% = 1/10

Interest being compounded annually after four years

​$$10^4 : 11^4$$​​
10000: 14641
14641 unit = 21,961.50
1 = 1.5
10000 = 15000
∴ Option b is the correct answer.