Principal from the interest — Aptitude Question
Principal from the interest: A sum earns ₹1,750 as simple interest in 5 years at 7% per annum. What is the principal? Answer and worked solution on CodeKairo.
- Topic: Simple & Compound Interest
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
A sum earns ₹1,750 as simple interest in 5 years at 7% per annum. What is the principal?
Options
- ₹4,000
- ₹4,500
- ₹5,000
- ₹5,500
Show the answer and the worked solution
Correct answer: C. ₹5,000
Worked solution
- Total rate = 7 × 5 = 35%.
- P = 1,750 ÷ 0.35 = ₹5,000.
Answer: ₹5,000.
The idea
Rearrange P = 100 × SI / (R × T). Combining rate and time into one percentage keeps it to a single division.
Shortcut. 35% of P is 1,750, so 1% of P is 50 and P is 5,000. Back-check: 7% of 5,000 is 350 a year, × 5 = 1,750.
Common trap. ₹4,500 looks right if 1,750 ÷ 0.35 is estimated rather than worked; 35% of 4,500 is only ₹1,575, short of the ₹1,750 stated.
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