Example 1 · level 1
Joseph deposits ₹5,750 in a post office scheme at 4% per annum simple interest. How much interest is earned in 4 years?
Show solution
- SI = 5,750 × 4 × 4 / 100
- = ₹920.
Answer: ₹920
SSC & BANK EXAMS: QUANTITATIVE APTITUDE · SIMPLE & COMPOUND INTEREST
Simple interest
SI = P × R × T / 100. Amount = P + SI.
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Worked examples
Example 2 · level 2
A sum of ₹13,500 lent by Tenzin becomes ₹17,550 in 3 years at simple interest. Find the rate of interest per annum (in %).
Show solution
- SI = 17,550 − 13,500 = ₹4,050.
- R = 4,050 × 100 / (13,500 × 3) = 10%.
Answer: 10 %
Example 3 · level 3
At simple interest, a sum becomes 3 times itself in 4 years. In how many years will it become 5 times itself?
Show solution
- 3 times → interest = 2P in 4 years, so P of interest takes 2 years.
- 5 times → interest = 4P, which takes 4 × 2 = 8 years.
Answer: 8 years