RRB PO Exam is going to be conducted in less than a month. In such a situation, it is very important to prepare the complex topics on a priority basis, as they require much practice and to practice, you require time. As it cannot be prepared in the last 5-6 days so this is the appropriate time to prepare such topics. Preparing well for this topic not only boosts your Quant score but also strengthens your performance in related topics like Profit & Loss, Ratio, and Data Interpretation. In this blog, we are going to discuss the common types of questions asked from simple and compound interest with examples, along with some preparation tips. We will also provide a PDF that contains questions for practice.
Download Simple and Compound Interest Questions PDF
In this section, we are providing a PDF that contains Simple and Compound Interest question PDF along with solution to get yourself exam ready for the upcoming RRB PO Exams.
Weightage of Simple and Compound Interest Questions in RRB PO Exams
In this section, we are giving an estimation of the weightage of simple and compound interest questions in RRB PO Exams.
| Topic | Approx. No. of Questions | Difficulty Level |
| Simple Interest | 2–3 | Easy to Moderate |
| Compound Interest | 2–3 | Moderate |
| Combined (SI + CI or Data-based Interest) | 1–2 | Moderate to High |
Key Concepts and Formulas
To solve SI and CI questions efficiently, it’s essential to memorise and understand the key formulas. In this section, we are discussing the same.
Simple Interest (SI)
Formula:
SI=P×R×T/100
Where,
P = Principal
R = Rate of Interest
T = Time (in years)
Compound Interest (CI)
Formula:
CI=P(1+R/100)T−P
Or,
CI=A−P, where A = Final Amount.
Difference between CI and SI
For 2 years:
CI−SI=P×(R/100)2
For 3 years:
CI−SI=P×(R/100)2×(300+R/100)
Understanding these differences helps solve advanced-level questions quickly.
Common Types of Questions Asked in RRB PO Exams
You can see a variety of questions asked about this topic in the exam. Here, we are discussing the common types of questions that were asked in previous years’ examinations.
Basic Formula-based Problems
These are Direct applications of SI or CI formulas. Example:
Question:
Find the simple interest on ₹6,000 at 10% per annum for 3 years.
Solution:
Using the formula
SI=P×R×T/100
SI=6000×10×3/100=₹1800
Answer: ₹1800
Difference between SI and CI
Finding the extra amount earned in CI over SI.
Example:
Question:
Find the difference between compound interest and simple interest on ₹5,000 at 8% per annum for 2 years.
Solution:
Difference = P×(R/100)2
= 5000×(8/100)2=5000×64/10000=₹32
Answer: ₹32
Rate or Time Calculation
In this type of question, interest is given along with principal, you’ve to find the missing values.
Example: If the simple interest on ₹4,000 for 2 years is ₹800, find the rate of interest per annum.
Solution:
Using SI=P×R×T/100
800=4000×R×2/100
R=800×100/4000×2=10%
Answer: 10% per annum
Successive Rates
Compound interest questions involving different rates for different years.
For example: Find the compound interest on ₹10,000 for 2 years if the rate of interest is 10% for the first year and 12% for the second year.
Solution:
Amount after 1st year = 10000×110/100=11000
Amount after 2nd year = 11000×112/100=12320
Compound Interest = 12320−10000=₹2320
Answer: ₹2320
Data Interpretation-based Interest Questions
These types of simple and compound interest questions are generally found in Mains, where you analyse tabular or graph-based interest data.
Question:
A table shows investments of three persons at 10% simple interest for 2 years.
| Person | Principal (₹) |
| A | 5,000 |
| B | 8,000 |
| C | 10,000 |
Find the total interest earned by all three together.
Solution:
Interest (A) = 5000×10×2/100=₹1000
Interest (B) = 8000×10×2/100=₹160
Interest (C) = 10000×10×2/100=₹2000
Total Interest = ₹1000 + ₹1600 + ₹2000 = ₹4600
Answer: ₹4600
Combined Arithmetic Questions –
In this, mixed types of questions are asked. Interest mixed with ratio, profit & loss, or percentage.
Question:
A man invests ₹8,000 at 10% compound interest per annum. He uses the interest earned after 2 years to buy goods and sells them at 25% profit. Find his total profit after selling the goods.
Solution:
Compound Interest for 2 years
=8000×(1+10/100)2−8000=8000×1.21−8000=₹1680
Profit on selling goods = 25% of ₹1680 = 25/100×1680=₹420
Total Profit = ₹420
Preparation Strategy for RRB PO Simple and Compound Interest Questions
In this section, we are going to discuss how you should prepare such a complex but scoring topic to get a better score in the examination.
- Learn quick multiplication and fraction-percentage conversions. These small improvements can save 10-15 seconds per question in the exam.
- Before heading towards solving the questions, revise fundamental formulas and relationships between principal, rate, time, and amount. This will help you in applying the formula while solving questions.
- Begin with simple formula-based problems before moving to multi-concept questions that mix SI, CI, and percentages. For example, instead of calculating CI year by year, use the formula directly or apply percentage increase logic. Also, always check the time unit (years, months, or days) before applying the formula.
- Include at least two Arithmetic sectional mocks per week. Review every mistake and note where you commit mistakes- is it conceptual, calculative, or careless? Also, while solving the compound interest questions, make sure you avoid rounding too early in compound interest questions, try to keep at least two decimal points until the final answer.
- Make a formula sheet with all interest-related formulas and short tricks. Regular revision helps retain them during the final week before the exam.
Conclusion
In this article, we have discussed the types of common questions asked, along with the PDF to solve. To solve questions from more such topics, you can buy our test series, where you can get reattempt the full-length mock tests and get a Detailed Comparison with the Topper, compare your Time, Score, Accuracy, Correct/Wrong Answers, and even the Average Performance side-by-side.
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IBPS RRB PO 2025 Related Link
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FAQs
In Prelims, they are mostly formula-based, while in Mains, logical and data-driven variations are common.
Remember CI= P(1+R/100)T−P for quick calculations.
Yes, some questions ask for the difference between SI and CI or mix both concepts.
Use percentage growth shortcuts or the formula A= P(1+R/100)T directly instead of calculating year by year. This saves time and reduces calculation errors in multi-year problems.
Simple Interest involves a fixed return every year, while Compound Interest grows year over year as interest is added to the principal. Recognizing whether the question mentions “interest on interest” helps you identify the type instantly.
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