Question

The compound interest on a certain sum of money at 5% per annum for 2 years is ₹ 4100. Find the simple interest on the same sum for 3 years at 8% per annum.

Answer 1

Given:

• Compound interest (C.I.) = ₹ 4100
• Rate of interest (r) = 5% per annum
• Time (n) = 2 years
• Need to find: Simple interest (S.I.) on the same sum for 3 years at 8% per annum

Step-wise calculation:

1. Let the principal be P.

2. Relation for compound interest for 2 years:

`C.I. = P(1 + r/100)^n - P`

`C.I. = P[(1 + 5/100)^2 - 1]`

3. Substituting the known C.I.:

4100 = P[(1.05)² – 1]

4100 = P(1.1025 – 1)]

4100 = P(0.1025)

4. Solving for P:

`P = 4100/0.1025`

P = 40000

5. Now, find simple interest for 3 years at 8% per annum:

`S.I. = (P xx r xx t)/100`

`S.I. = (40000 xx 8 xx 3)/100`

S.I. = 9600

The simple interest on the same sum for 3 years at 8% per annum is ₹ 9600.