In the previous section, we learned the Simple Interest (SI) and Compound Interest (CI) formulas and solved a few examples to understand how these formulas work. Now it’s time to apply those concepts by solving Simple Interest questions.
This page includes all the important types of Simple Interest questions that are commonly asked in competitive exams. The questions are arranged in increasing order of difficulty, starting from Easy, then Medium, followed by Difficult and Exam-Level questions. We recommend solving them in sequence instead of skipping ahead, as each set builds on the concepts learned in the previous one.
Detailed solutions are also provided. However, try to solve each question on your own before referring to the solution. This approach will strengthen your understanding, improve your problem-solving skills, and boost your confidence for the exam.
After completing these practice questions, you will have a solid understanding of how to apply the Simple Interest formula in different real-life and competitive exam scenarios.
You can also explore our Quantitative Aptitude Notes to revise concepts, Quantitative Aptitude Formula Sheet for quick revision, Practice Questions for other maths topics, and Previous Year Questions (PYQs) to understand the pattern of questions asked in competitive exams.
If you’re preparing for SSC, RRB, Banking, Defence, Police, or other government exams, don’t forget to check our Quantitative Aptitude Syllabus page, which covers the complete maths syllabus for various competitive exams.
You can also use our Math Calculators to verify answers and speed up your calculations.
Quick Revision: SI Formulas
| Variable | Formula |
| Simple Interest | SI = (P × R × T) ÷ 100 |
| Principal (SI) | P = (SI × 100) ÷ (R × T) |
| Rate (SI) | R = (SI × 100) ÷ (P × T) |
| Time (SI) | T = (SI × 100) ÷ (P × R) |
Question 1: A Station Master at Lucknow Junction deposits ₹20,000 in a savings account at 6% simple interest per annum for 3 years. Find the Simple Interest earned.
Solution
Given
Principal Amount (P) = ₹20,000
Rate of Interest (R) = 6% per annum
Time (T) = 3 years
Formula Used
Simple Interest (SI) = (P × R × T) ÷ 100
Substitute the Values
SI = (20,000 × 6 × 3) ÷ 100
SI = 3,60,000 ÷ 100
SI = ₹3,600
Answer
The Simple Interest earned is ₹3,600.
Note: Always write the values of Principal (P), Rate (R), and Time (T) before applying the formula. This simple habit reduces mistakes and helps you solve questions more quickly during competitive exams.
Shortcut (SSC, RRB, Banking, Defence & Police Exams)
Since the interest is simple interest, multiply the rate by the number of years first.
Total Interest = 6% × 3 = 18%
Now find 18% of ₹20,000.
18% of ₹20,000 = ₹3,600
Question 2: A Bank Manager invests ₹45,000 in a fixed deposit at 8% simple interest per annum for 5 years. Calculate the Simple Interest.
Solution
Given
Principal Amount (P) = ₹45,000
Rate of Interest (R) = 8% per annum
Time (T) = 5 years
Formula Used
Simple Interest (SI) = (P × R × T) ÷ 100
Substitute the Values
SI = (45,000 × 8 × 5) ÷ 100
SI = 18,00,000 ÷ 100
SI = ₹18,000
Answer
The Simple Interest earned is ₹18,000.
Shortcut
Since the rate of interest is 8% per year for 5 years, the total interest is:
8% × 5 = 40%
Now calculate 40% of ₹45,000.
40% of ₹45,000 = ₹18,000
Question 3: An Assistant Section Officer (ASO) invests ₹36,000 at 10% simple interest per annum for 18 months. Find Simple Interest.
Solution
Given
Principal Amount (P) = ₹36,000
Rate of Interest (R) = 10% per annum
Time (T) = 18 months = 18 ÷ 12 = 1.5 years
Formula Used
Simple Interest (SI) = (P × R × T) ÷ 100
Substitute the Values
SI = (36,000 × 10 × 1.5) ÷ 100
SI = 5,40,000 ÷ 100
SI = ₹5,400
Answer
The Simple Interest earned is ₹5,400.
Exam Tip (SSC, RRB, Banking, Defence & Police Exams)
Note: Whenever the time is given in months, and interest rate is in per annum , first convert it into years before applying the Simple Interest formula.
Question 4: A Colonel in the Indian Army invests ₹80,000 at 7.5% simple interest per annum for 4 years. Find the Total Amount received at maturity.
Solution
Given
Principal Amount (P) = ₹80,000
Rate of Interest (R) = 7.5% per annum
Time (T) = 4 years
Formula Used
Simple Interest (SI) = (P × R × T) ÷ 100
Amount (A) = P + SI
Substitute the Values
SI = (80,000 × 7.5 × 4) ÷ 100
SI = 24,00,000 ÷ 100
SI = ₹24,000
Now,
Amount = ₹80,000 + ₹24,000
Amount = ₹1,04,000
Answer
The total amount received at maturity is ₹1,04,000.
Note: In Simple Interest questions, “Amount” or “Maturity Amount” means the total money received at the end of the investment period.
Amount = Principal + Simple Interest
Question 5: An employee of Tata Steel deposits ₹60,000 at 9% simple interest per annum for 2 years. Calculate the Simple Interest.
Solution
Given
Principal Amount (P) = ₹60,000
Rate of Interest (R) = 9% per annum
Time (T) = 2 years
SI = (60,000 × 9 × 2) ÷ 100
SI = 10,80,000 ÷ 100
SI = ₹10,800
Answer
The Simple Interest earned is ₹10,800.
Question 6: A resident of Unnao earns ₹4,800 as simple interest in 4 years at 6% per annum. Find the Principal Amount invested.
Solution
Given
Simple Interest (SI) = ₹4,800
Rate of Interest (R) = 6% per annum
Time (T) = 4 years
Formula Used
Principal Amount (P) = (SI × 100) ÷ (R × T)
P = (4,800 × 100) ÷ (6 × 4)
P = 4,80,000 ÷ 24
P = ₹20,000
Answer
The Principal Amount invested is ₹20,000.
Question 7: An employee of Chittaranjan Locomotive Works (CLW) earns ₹7,200 as simple interest in 3 years at 8% per annum. Find the Principal Amount.
Solution
Given
Simple Interest (SI) = ₹7,200
Rate of Interest (R) = 8% per annum
Time (T) = 3 years
P = (7,200 × 100) ÷ (8 × 3)
P = 7,20,000 ÷ 24
P = ₹30,000
Answer
The Principal Amount invested is ₹30,000.
Question 8: A Bank Manager invests ₹50,000 and earns ₹12,500 as simple interest in 5 years. Find the Rate of Interest per annum.
Solution
Given
Principal Amount (P) = ₹50,000
Simple Interest (SI) = ₹12,500
Time (T) = 5 years
Formula Used
Rate of Interest (R) = (SI × 100) ÷ (P × T)
R = (12,500 × 100) ÷ (50,000 × 5)
R = 12,50,000 ÷ 2,50,000
R = 5%
Answer
The Rate of Interest is 5% per annum.
Question 9: A Station Master invests ₹24,000 and receives ₹4,320 as simple interest in 3 years. Calculate the Rate of Interest.
Solution
Given
Principal Amount (P) = ₹24,000
Simple Interest (SI) = ₹4,320
Time (T) = 3 years
R = (4,320 × 100) ÷ (24,000 × 3)
R = 4,32,000 ÷ 72,000
R = 6%
Answer
The Rate of Interest is 6% per annum.
Question 10: An ASO invests ₹30,000 at 8% simple interest per annum and earns ₹7,200 as interest. Find the Time Period.
Solution
Given
Principal Amount (P) = ₹30,000
Rate of Interest (R) = 8% per annum
Simple Interest (SI) = ₹7,200
Formula Used
Time (T) = (SI × 100) ÷ (P × R)
T = (7,200 × 100) ÷ (30,000 × 8)
T = 7,20,000 ÷ 2,40,000
T = 3 years
Answer
The Time Period is 3 years.
Question 11: A Colonel in the Indian Army invests ₹75,000 at 10% simple interest per annum and receives ₹22,500 as interest. Calculate the Time Period.
Solution
Given
Principal Amount (P) = ₹75,000
Rate of Interest (R) = 10% per annum
Simple Interest (SI) = ₹22,500
T = (22,500 × 100) ÷ (75,000 × 10)
T = 22,50,000 ÷ 7,50,000
T = 3 years
Answer
The Time Period is 3 years.
Question 12: A resident of Chandigarh invests ₹40,000 at 12% simple interest per annum for 8 quarters. Calculate the Simple Interest.
Solution
Given
Principal Amount (P) = ₹40,000
Rate of Interest (R) = 12% per annum
Time (T) = 8 quarters = 2 years (1 quarter=3 Months)
SI = (40,000 × 12 × 2) ÷ 100
SI = 9,60,000 ÷ 100
SI = ₹9,600
Answer
The Simple Interest earned is ₹9,600.
Exam Tip (SSC, RRB, Banking, Defence & Police Exams)
Remember to convert quarters into years before applying the Simple Interest formula.
4 Quarters = 1 Year
So,
8 Quarters = 2 Years
SI= 24% of 40000= ₹9,600
Question 13: A Tata Steel engineer invests ₹65,000 at 9% simple interest per annum for 5 years. Find the Total Amount.
Solution
Given
Principal Amount (P) = ₹65,000
Rate of Interest (R) = 9% per annum
Time (T) = 5 years
Simple Interest = (65,000 × 9 × 5) ÷ 100
Simple Interest = ₹29,250
Amount = Principal + Simple Interest
Amount = ₹65,000 + ₹29,250
Amount = ₹94,250
Answer
The Total Amount is ₹94,250.
Question 14: A Bank Manager invested ₹50,000. At the end of 4 years, the total amount became ₹66,000. Find the Rate of Interest per annum.
Solution
Given
Principal Amount (P) = ₹50,000
Amount (A) = ₹66,000
Time (T) = 4 years
Simple Interest = Amount − Principal
SI = ₹66,000 − ₹50,000
SI = ₹16,000
R = (16,000 × 100) ÷ (50,000 × 4)
R = 16,00,000 ÷ 2,00,000
R = 8%
Answer
The Rate of Interest is 8% per annum.
Shortcut:
Since the Amount increased from ₹50,000 to ₹66,000, first find the percentage increase.
Increase = ₹66,000 − ₹50,000 = ₹16,000
Percentage Increase = (16,000 ÷ 50,000) × 100 = 32%
This 32% interest was earned over 4 years.
Rate of Interest = 32% ÷ 4 = 8% per annum
Question 15: Two Station Masters, one posted at Lucknow Junction and the other at Kanpur Central, each invested ₹40,000. The first invests at 8% per annum for 4 years, while the second invests at 10% per annum for 3 years. Who earns more Simple Interest, and by how much?
Solution
Given
First Station Master
Principal Amount = ₹40,000
Rate = 8% per annum
Time = 4 years
Second Station Master
Principal Amount = ₹40,000
Rate = 10% per annum
Time = 3 years
Simple Interest of First Station Master
SI = (40,000 × 8 × 4) ÷ 100
SI = ₹12,800
Simple Interest of Second Station Master
SI = (40,000 × 10 × 3) ÷ 100
SI = ₹12,000
Difference = ₹12,800 − ₹12,000 = ₹800
Answer
The Station Master posted at Lucknow Junction earns ₹800 more as Simple Interest.
Exam Tip (SSC, RRB, Banking, Defence & Police Exams)
When the Principal Amount is the same, compare the product of Rate × Time (R × T) first.
- First Investment: 8 × 4 = 32
- Second Investment: 10 × 3 = 30
Since 32 > 30, the first investment will always earn more Simple Interest.
Question 16: Two employees of Tata Steel each invest ₹50,000 at 9% simple interest per annum. One invests for 3 years, while the other invests for 5 years. Find the difference in Simple Interest earned.
Solution
Given
Principal Amount = ₹50,000
Rate = 9% per annum
Time = 3 years and 5 years
Simple Interest for 3 years
SI = (50,000 × 9 × 3) ÷ 100
SI = ₹13,500
Simple Interest for 5 years
SI = (50,000 × 9 × 5) ÷ 100
SI = ₹22,500
Difference = ₹22,500 − ₹13,500
Difference = ₹9,000
Answer
The difference in Simple Interest earned is ₹9,000.
Question 17: An ASO invested the same principal amount for 5 years. If the rate of interest is increased from 6% to 8% per annum, the Simple Interest increases by ₹2,400. Find the Principal Amount.
Solution
Given
Increase in Rate = 8% − 6% = 2%
Increase in Simple Interest = ₹2,400
Time = 5 years
Increase in SI = (Principal × Increase in Rate × Time) ÷ 100
2,400 = (P × 2 × 5) ÷ 100
2,400 = P ÷ 10
P = ₹24,000
Answer
The Principal Amount invested is ₹24,000.
Exam Shortcut (SSC, RRB, Banking, Defence & Police Exams)
The rate increases from 6% to 8%, so the increase is 2% per annum.
Over 5 years, the total increase in Simple Interest is:
2% × 5 = 10% of the Principal Amount
Since this 10% = ₹2,400,
10% of Principal = ₹2,400
100% of Principal = ₹2,400 × 10 = ₹24,000
Question 18: A Colonel in the Indian Army invested a certain sum at 10% simple interest per annum. If the investment period is increased from 4 years to 7 years, the Simple Interest increases by ₹9,000. Find the Principal Amount.
Solution
Given
Rate of Interest = 10% per annum
Increase in Time = 7 − 4 = 3 years
Increase in Simple Interest = ₹9,000
Increase in SI = (Principal × Increase in Time × Rate) ÷ 100
9,000 = (P × 3 × 10) ÷ 100
9,000 = 3P ÷ 10
P = ₹30,000
Answer
The Principal Amount invested is ₹30,000.
Exam Shortcut (SSC, RRB, Banking, Defence & Police Exams)
The investment period increases by 3 years at 10% per annum.
So, the additional interest earned is:
3 × 10% = 30% of the Principal
Since 30% = ₹9,000,
10% = ₹3,000
100% = ₹30,000
Therefore, Principal = ₹30,000.
Question 19: Two residents of Unnao invest money at 8% simple interest per annum for 5 years. One invests ₹20,000 more than the other and therefore earns ₹8,000 more as Simple Interest. Verify whether this statement is correct. If not, determine the actual difference in Simple Interest.
Solution
Given
Difference in Principal = ₹20,000
Rate of Interest = 8% per annum
Time = 5 years
Claimed Difference in SI = ₹8,000
Difference in SI
= (20,000 × 8 × 5) ÷ 100
= ₹8,000
The calculated difference matches the given statement.
Answer
Yes, the statement is correct. The difference in Simple Interest earned is ₹8,000.
Question 20: An employee of Chittaranjan Locomotive Works (CLW) invested a certain amount at 12% simple interest per annum. After 5 years, the total amount became ₹1,12,000. Find the Principal Amount and the Simple Interest earned.
Solution
Given
Amount (A) = ₹1,12,000
Rate of Interest (R) = 12% per annum
Time (T) = 5 years
Simple Interest for 5 years
= 12% × 5
= 60% of the Principal
Amount = Principal + Simple Interest
₹1,12,000 = 160% of the Principal
Principal = (1,12,000 × 100) ÷ 160
Principal = ₹70,000
Simple Interest = ₹1,12,000 − ₹70,000
Simple Interest = ₹42,000
Answer
Principal Amount = ₹70,000
Simple Interest Earned = ₹42,000
Exam Shortcut (SSC, RRB, Banking, Defence & Police Exams)
At 12% per annum for 5 years,
Simple Interest = 12% × 5 = 60% of the Principal
So,
SI : Principal = 60 : 100 = 3 : 5
Therefore,
Amount : Principal = (3 + 5) : 5 = 8 : 5
Since,
Amount = ₹1,12,000
Principal = ₹1,12,000 × 5/8
= ₹70,000
Simple Interest = ₹1,12,000 − ₹70,000
= ₹42,000
Question 21: A Bank Manager and a Station Master at Lucknow Junction each invest ₹60,000 at simple interest. The Bank Manager invests at 8% per annum for 5 years, while the Station Master invests at 10% per annum for 4 years.
- Find the Simple Interest earned by each person.
- Find the Total Amount received by each person.
- Who earns more interest, and by how much?
Solution
Given
Bank Manager
Principal Amount = ₹60,000
Rate = 8% per annum
Time = 5 years
Station Master
Principal Amount = ₹60,000
Rate = 10% per annum
Time = 4 years
Bank Manager
Simple Interest
= (60,000 × 8 × 5) ÷ 100
= ₹24,000
Amount
= ₹60,000 + ₹24,000
= ₹84,000
Station Master
Simple Interest
= (60,000 × 10 × 4) ÷ 100
= ₹24,000
Amount
= ₹60,000 + ₹24,000
= ₹84,000
Difference in Simple Interest
= ₹24,000 − ₹24,000
= ₹0
Answer
- Simple Interest earned by the Bank Manager = ₹24,000
- Simple Interest earned by the Station Master = ₹24,000
- Total Amount received by each = ₹84,000
- Both earn the same Simple Interest. There is no difference.
Exam Shortcut (SSC, RRB, Banking, Defence & Police Exams)
Since the Principal Amount is the same (₹60,000), first compare Rate × Time.
Bank Manager: 8 × 5 = 40
Station Master: 10 × 4 = 40
Since Rate × Time is the same, both earn the same Simple Interest.
Simple Interest
= 40% of ₹60,000
= ₹24,000
Total Amount
= Principal + Simple Interest
= ₹60,000 + ₹24,000
= ₹84,000
Therefore,
- Simple Interest earned by each = ₹24,000
- Total Amount received by each = ₹84,000
- Difference in Simple Interest = ₹0
What We Learnt in This Section
In this section, you practised solving Simple Interest questions using formulas as well as quick exam shortcuts. You also learnt how to calculate the Principal, Rate, Time, Amount, and Simple Interest, compare two investments, and solve real-life exam-based problems with confidence.
To strengthen your Quantitative Aptitude preparation, continue learning with our Simple Interest & Compound Interest section, Percentage, Profit and Loss, Discount, and Ratio and Proportion pages. These topics are closely connected and are frequently asked together in SSC, RRB, Banking, Defence, Police, and other competitive exams.
FAQ:
1. How do you calculate Simple Interest?
Simple Interest is calculated using the formula:
SI = (P × R × T) ÷ 100
where:
P = Principal Amount
R = Rate of Interest (per annum)
T = Time (in years)
2. How do you calculate the Total Amount if the Principal and Simple Interest are given?
The Total Amount is the sum of the Principal Amount and the Simple Interest.
Amount = Principal + Simple Interest
or
A = P + SI
3. What is the formula to calculate the Principal Amount if Simple Interest, Rate, and Time are given?
If the Simple Interest, Rate of Interest, and Time are known, the Principal Amount is calculated using:
P = (100 × SI) ÷ (R × T)
4. What is the formula to calculate the Rate of Interest if Simple Interest, Principal, and Time are given?
The Rate of Interest is calculated using:
R = (100 × SI) ÷ (P × T)
5. What is the formula to calculate the Time Period in Simple Interest?
If the Principal Amount, Rate of Interest, and Simple Interest are known, the Time Period is calculated using:
T = (100 × SI) ÷ (P × R)
Important Link Related to Simple Interest & Compound Interest
- Simple Interest & Compound Interest
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- Simple Interest & Compound Interest PYQs SSC, RRB, Banking & Defence Exams With Solution.