Amount after simple interest — Aptitude Question
Amount after simple interest: What amount will ₹15,000 grow to in 4 years at 9% per annum simple interest? Answer and worked solution on CodeKairo.
- Topic: Simple & Compound Interest
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 50 seconds
Question
What amount will ₹15,000 grow to in 4 years at 9% per annum simple interest?
Options
- ₹19,800
- ₹20,400
- ₹21,000
- ₹21,600
Show the answer and the worked solution
Correct answer: B. ₹20,400
Worked solution
- Total rate = 9 × 4 = 36%.
- Interest = 36% of 15,000 = ₹5,400.
- Amount = 15,000 + 5,400 = ₹20,400.
Answer: ₹20,400.
The idea
Amount = principal + interest under simple interest, or P(1 + RT/100) in one step.
Shortcut. One multiplication: 15,000 × 1.36. A third of 15,000 is 5,000 and 36% is 400 more, so the interest is ₹5,400 and the amount ₹20,400.
Common trap. ₹21,000 — rounding the rate up to 10% (40% of 15,000 = 6,000); at 9% the four years add 36%, only ₹5,400.
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