Practice Questions
Concept Explanation
The amount is the total value at the end of the period — principal plus simple interest.
Key Formulas
- A = P + SI
- A = P(1 + RT/100)
- A = P + (PRT/100)
Example
P = Rs. 5,000, R = 10%, T = 2 years. SI = Rs. 1,000. Amount = Rs. 6,000.
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Q1 EasyFind the amount on Rs. 7500 for 2 years at 8% SI.ExplanationFormula: A = P + (P × R × T)/100. SI = (7500 × 8 × 2)/100 = Rs. 1,200. Amount = 7500 + 1200 = Rs. 8,700. Answer: C.
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Q2 EasyWhat will Rs. 500 amount to in 10 years after its deposit in a bank which pays simple interest of 10% per annum?ExplanationA = P(1 + RT/100) = 500(1 + 10 × 10/100) = 500(1 + 1) = Rs. 1,000. Answer: C.
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Q3 EasyFind the amount on Rs. 6,000 at 12% simple interest for 3 years.ExplanationSI = (6000 × 12 × 3)/100 = Rs. 2,160. Amount = 6000 + 2160 = Rs. 8,160. Answer: C.
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Q4 EasyA principal of Rs. 4,000 is lent at 8% SI for 5 years. The amount is:ExplanationA = 4000(1 + 8 × 5/100) = 4000 × 1.4 = Rs. 5,600. Answer: C.
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Q5 EasyAmount on Rs. 15,000 at 6% SI for 2 years is:ExplanationSI = (15000 × 6 × 2)/100 = Rs. 1,800. Amount = 15000 + 1800 = Rs. 16,800. Answer: B.
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Q6 EasyFind the amount if SI on Rs. 10,000 at 12% for 3 years is added to the principal.ExplanationSI = (10000 × 12 × 3)/100 = Rs. 3,600. Amount = 10000 + 3600 = Rs. 13,600. Answer: C.
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Q7 MediumA sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is:ExplanationSI for 1 year = 854 − 815 = Rs. 39. SI for 3 years = 39 × 3 = Rs. 117. Principal = 815 − 117 = Rs. 698. Answer: C.
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Q8 MediumA sum of Rs. 12,500 amounts to Rs. 15,500 in 4 years at the rate of simple interest. The rate of interest is:ExplanationSI = 15500 − 12500 = Rs. 3,000. R = (100 × SI)/(P × T) = (100 × 3000)/(12500 × 4) = 300000/50000 = 6%. Answer: D.
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Q9 MediumRs. 9,000 is invested at 10% SI for 2.5 years. Find the amount.ExplanationSI = (9000 × 10 × 2.5)/100 = Rs. 2,250. Amount = 9000 + 2250 = Rs. 11,250. Answer: C.
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Q10 MediumIf the amount on a sum at 5% SI for 4 years is Rs. 7,200, the principal is:ExplanationA = P(1 + RT/100) ⇒ 7200 = P(1 + 5 × 4/100) = P × 1.2 ⇒ P = 7200/1.2 = Rs. 6,000. Answer: B.
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Q11 MediumA sum becomes Rs. 5,760 in 2 years at 8% SI. What was the principal?Explanation5760 = P(1 + 8 × 2/100) = P × 1.16 ⇒ P = 5760/1.16 = Rs. 5,000. Answer: B.
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Q12 HardA sum amounts to Rs. 9800 after 5 years and Rs. 12005 after 8 years at the same rate of simple interest. The principal is:ExplanationInterest for 3 years = 12005 − 9800 = Rs. 2,205. Interest per year = 2205/3 = Rs. 735. Interest for 5 years = 735 × 5 = Rs. 3,675. Principal = 9800 − 3675 = Rs. 6,125. Answer: B.
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Q13 HardA sum of money doubles itself in 8 years at simple interest. The amount after 12 years on the same principal and rate is how many times the principal?ExplanationIf money doubles in 8 years, SI in 8 years = P, so RT/100 = 1 ⇒ R × 8/100 = 1 ⇒ R = 12.5%. In 12 years, SI = P × 12.5 × 12/100 = 1.5P. Amount = P + 1.5P = 2.5P. Answer: B.
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Q14 HardAt 9% SI, a sum of Rs. 8,000 becomes what amount in 2 years 6 months?ExplanationT = 2.5 years. SI = (8000 × 9 × 2.5)/100 = Rs. 1,800. Amount = 8000 + 1800 = Rs. 9,800. Answer: B.
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DS1 Easy
What is the amount under simple interest?
Statement IPrincipal is Rs. 7,500 at 8% per annum for 2 years.
Statement IIThe simple interest for the period is Rs. 1,200.
ExplanationStatement I alone: A = 7500(1 + 8 × 2/100) = Rs. 8,700. Statement II alone needs the principal to find amount. So I alone is sufficient. Answer: A. -
DS2 Easy
What is the amount?
Statement IPrincipal is Rs. 6,000.
Statement IIRate is 12% SI and time is 3 years.
ExplanationNeed P, R and T. Together: SI = (6000 × 12 × 3)/100 = Rs. 2,160; Amount = Rs. 8,160. Neither alone is enough. Answer: C.
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DS3 Medium
Is the amount greater than Rs. 10,000?
Statement IP = Rs. 9,000 at 10% SI for 2.5 years.
Statement IISI for the period is Rs. 2,250.
ExplanationStatement I: SI = (9000 × 10 × 2.5)/100 = Rs. 2,250; Amount = 9000 + 2250 = Rs. 11,250 > 10,000. Statement II alone: Amount = P + 2250, but P is unknown. So I alone is sufficient. Answer: A. -
DS4 Hard
What is the principal?
Statement IThe sum amounts to Rs. 9,800 after 5 years and Rs. 12,005 after 8 years at the same SI rate.
Statement IIInterest for 3 years is Rs. 2,205.
ExplanationStatement I alone: SI for 3 years = 2205; SI/year = 735; SI for 5 years = 3675; P = 9800 − 3675 = Rs. 6,125. Statement II alone does not give the amount after 5 years. Answer: A.