PYQ Bank — Bank PO / Clerk

Difference between amounts in 4 years and 2 years = 2,800 - 2,400 = ₹400, which represents interest for 2 years.

So, interest per year = 200.

From SI = P × R × T / 100, we have 400 = P × R × 2 / 100.

Also, Amount after 2 years = P + 400 = 2,400, so P = ₹2,000.

Therefore, 400 = 2000 × R × 2 / 100, giving R = 10% p.a.

Amount = Principal × (1 + R1/100) × (1 + R2/100) × (1 + R3/100).

So 13,310 = 10,000 × (1 + R1/100) × (1 + R1+5/100) × (1 + R1+10/100).

This gives 1.331 = (1 + R1/100) × (1 + R1+5/100) × (1 + R1+10/100).

Testing R1 = 10: 1.10 × 1.15 × 1.20 = 1.518 (too high).

Testing R1 = 5: 1.05 × 1.10 × 1.15 = 1.328875 ≈ 1.331 ✓.

This requires systematic testing and understanding of varying rate compound interest—a challenging problem.