How long will it take for a principal of ₹450 to earn ₹81 as simple interest…
2023
How long will it take for a principal of ₹450 to earn ₹81 as simple interest at 4.5% per annum?
Answer: A. 4 years — ConceptFor simple interest, SI = (P × R × T) / 100, where P is the principal, R is the annual rate in percent, and T is the time in years. When time is…
- A.
4 years
- B.
2.5 years
- C.
3.5 years
- D.
2 years
Attempted by 10 students.
Show answer & explanation
Correct answer: A
Concept
For simple interest, SI = (P × R × T) / 100, where P is the principal, R is the annual rate in percent, and T is the time in years.
When time is unknown, rearrange the formula as T = (100 × SI) / (P × R).
Application
Substitute P = ₹450, SI = ₹81, and R = 4.5 into the rearranged formula.
T = (100 × 81) / (450 × 4.5).
The numerator is 8100 and the denominator is 2025, so T = 8100 / 2025 = 4 years.
Cross-check
Using T = 4 years in the original formula gives SI = (450 × 4.5 × 4) / 100 = ₹81, which matches the stated interest.
Therefore, the required time is 4 years.