Simple Interest – Find the principal from two amounts: A sum amounts to Rs 2,240 in 2 years and Rs 2,600 in 5 years at simple interest. Find the principal (original sum).
Aptitude
Simple Interest
Difficulty: Easy
Choose an option
Answer
Correct Answer: Rs 2000
Explanation
Introduction / Context:Two amounts at different times let us compute the uniform annual SI and hence the principal in a linear SI model.
Given Data / Assumptions:
- A2 = Rs 2240
- A5 = Rs 2600
Concept / Approach:Annual SI = (A5 - A2) / (5 - 2). Then P = A2 - 2 * (annual SI).
Step-by-Step Solution:
Annual SI = (2600 - 2240) / 3 = 360 / 3 = Rs 120P = 2240 - 2 * 120 = 2240 - 240 = Rs 2000Verification / Alternative check:
A5 check: 2000 + 5 * 120 = 2600 (matches)Why Other Options Are Wrong:
- Rs 1880 / 2120 / 1960: do not fit both given amounts.
- Data inadequate: sufficient for SI.
Common Pitfalls:
- Mistaking the time gap.
Final Answer:Rs 2000.