Correct Answer - Option 1 : 10%
Given:
Amount = Rs. 2100 in 4 years at simple interest.
Amount = Rs. 2550 in 7 years at simple interest.
Formula:
Simple Interest = (Principal × Time × Rate)/100
Calculation:
Let “r” be the rate of simple interest.
According to the question,
Interest received in (7 – 4) years is
⇒ 2550 – 2100
⇒ Rs. 450
Interest received in 1 year = 450/3 = Rs. 150
Interest received in 4 years = 150 × 4 = Rs. 600
Principal = 2100 – 600 = Rs. 1500.
According to the formula used,
600 = (1500 × 4 × r)/100
⇒ r = (600 × 100)/(1500 × 4)
⇒ r = 10
∴ The rate of Interest is 10%.
