At a simple interest, a sum amounts to ₹ 1012 in 21/2

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At a simple interest, a sum amounts to ₹ 1012 in 2¹/₂ and becomes ₹ 1067.20 in 4 yr. What is the rate of interest

1. 2.5%
2. 3%
3. 4%
4. 5%

Correct Option: C

Given, T₁ = 2¹/₂ yr, T₂ = 4 Yr

According to the question.
[P + (P x R x 4)/100] - [P + (P x R x 2.5)/100] = 1067.20 - 1012 = 55.2
⇒ (1.5 x P x R)/100 = 55.2
⇒ PR = (552 x 100) / 15 = 3680

For 4 yr.
SI = PRT/100 = (3680 x 4)/100 = ₹ 147.2
∴ Sum (P) = 1067.2 - 147.2 = ₹ 920
We have, PR = 3680
∴ R = 3680/P = 3680/920 = 4%