A sum, when invested at 20% simple interest per annum, amounts to ₹2400 after 3 years. What is the simple interest (in ₹) on the same sum at the same rate in 1 year?

Correct option is C

Given:

Amount after 3 years = ₹2400

Rate of simple interest = 20% per annum

Time = 3 years

Formula Used:

Amount (A) = Principal (P) + Simple Interest (SI)

SI =$$\frac{P \times R \times T}{100}$$​​

Solution:

Let the principal be P.

The simple interest earned in 3 years is:

SI = $$\frac{P \times 20 \times 3}{100}$$​​

SI = 0.6P

Amount (A) = P + SI

2400 = P + 0.6P

2400 = 1.6P

P = $$\frac{2400}{1.6}$$​​

P = ₹1500

Calculate the simple interest for 1 year:

SI for 1 year = $$\frac{P \times R \times T}{100}$$​​

SI = $$\frac{1500 \times 20 \times 1}{100}$$​​

SI = ₹300

Therefore, the simple interest on the same sum at the same rate in 1 year is ₹300.

Option (C) is right.