Time from the interest — Aptitude Question
Time from the interest: In how many years will ₹6,000 earn ₹1,800 as simple interest at 5% per annum? Answer and worked solution on CodeKairo.
- Topic: Simple & Compound Interest
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
In how many years will ₹6,000 earn ₹1,800 as simple interest at 5% per annum?
Options
- 4
- 5
- 6
- 8
Show the answer and the worked solution
Correct answer: C. 6
Worked solution
- Yearly interest = 5% of 6,000 = ₹300.
- Years = 1,800 ÷ 300 = 6.
Answer: 6.
The idea
Find the interest for one year and divide. Simple interest accrues the same amount every year, which is what makes this work.
Shortcut. ₹1,800 is 30% of 6,000, and at 5% a year it takes 30 ÷ 5 = 6 years to build 30%.
Common trap. 5 — taking 5% of the amount ₹7,800 (₹390 a year) gives about 4.6 years, which rounds to it; interest is charged on the ₹6,000 only.
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