If the difference between the compound interest and simple interest at 17% on a sum of money for 2 years (compounded annually) is Rs. 433.50, then the sum (in Rs.) is:
1. 12,000
2. 20,000
3. 15,000
4. 25,000
1. 12,000
2. 20,000
3. 15,000
4. 25,000
Correct Answer – Option 3 : 15,000
Given:
Rate of interest = 17%
Time = 2 years
The difference between CI and SI = Rs. 433.50
Formula used:
Simple interest = P × R% × T
Calculation:
Let the principal be Rs. x.
SI = P × R% × T
⇒ SI = x × 17% × 2
⇒ SI = x × 17/100 × 2
⇒ SI = 34x/100
⇒ SI = 0.34x
In the case of CI:
1st year CI = P × R% × T
⇒ 1st year CI = x × 17% × 1
⇒ 1st year CI = 17x/100
⇒ 1st year CI = 0.17x
Amount after 1st year = P + CI
⇒ Amount = x + 0.17x
⇒ Amount = 1.17x
2nd year CI = 1.17x × 17% × 1
⇒ 2nd year CI = 0.1989x
Total CI = 1st year CI + 2nd year CI
⇒ CI = 0.17x + 0.1989x
⇒ CI = 0.3689x
Required difference = CI – SI
⇒ 433.50 = 0.3689x – 0.34x
⇒ 433.50 = 0.0289x
⇒ x = 433.50/0.0289
⇒ x = Rs. 15000
∴ The sum is Rs. 15000.