Data sufficiency for bank exams tests one thing: can you decide whether the given statements are enough to answer the question, without solving it fully? It is a frequently practiced topic for IBPS PO Mains, SBI PO Mains and other Mains-level exams, and it rewards logic more than calculation. This guide explains the elimination method for data sufficiency, the answer-option map and 10 solved data sufficiency questions with answers. Scroll to the end to download the free practice set PDF.
Table of Contents
What is Data Sufficiency?
A question is given, followed by two statements (I and II). You have to decide which statement(s) are needed to answer the question. “Sufficient” means the statement gives one unique answer. You do not have to calculate the final value (unless you want to confirm).
Standard answer options used in this post
- (a) Statement I alone is sufficient, but II alone is not
- (b) Statement II alone is sufficient, but I alone is not
- (c) Either I alone or II alone is sufficient
- (d) Both I and II together are needed
- (e) Even both together are not sufficient
The wording of options can change between exams, so always read the option list first.
Data Sufficiency Tricks: The Elimination Method
Follow these 3 steps in the same order every time.
- Check Statement I alone. Ask: does it give a unique answer?
- Check Statement II alone. Forget Statement I completely while doing this.
- Combine both only if neither is sufficient alone.
Answer map
| I alone | II alone | Together | Answer |
|---|---|---|---|
| Sufficient | Not sufficient | not needed | (a) |
| Not sufficient | Sufficient | not needed | (b) |
| Sufficient | Sufficient | not needed | (c) |
| Not sufficient | Not sufficient | Sufficient | (d) |
| Not sufficient | Not sufficient | Not sufficient | (e) |
Why this works: Once you test the statements alone, you automatically eliminate options. If either one alone is enough, options (d) and (e) are gone. If neither is enough alone, options (a), (b) and (c) are gone.
Quick Tricks to Save Time in Data Sufficiency
- Count unknowns and equations. If a question needs 2 unknowns, you need 2 independent equations. One statement giving only one equation is not enough.
- Do not solve fully. Set up the equation, count unknowns, and move on.
- Watch for “unique” answers. If a statement gives two possible answers (like ±8), it is not sufficient.
- Convert units early. Speed in km/h versus m/s hides many traps.
- Never use outside assumptions. Use only what the statements say.
10 Solved Data Sufficiency Questions with Answers
Directions: Each question is followed by two statements. Choose from (a) to (e) as per the options above.
Age and Percentage Based
Q1. What is the present age of Rohan?
I. Five years ago, Rohan’s age was twice his sister’s age at that time.
II. Rohan is 4 years older than his sister.
Solution: Let Rohan = R and sister = S.
- I alone: R − 5 = 2(S − 5). Two unknowns, one equation. Not sufficient.
- II alone: R = S + 4. Not sufficient.
- Together: S + 4 − 5 = 2S − 10, so S = 9 and R = 13.
Answer: (d)
Q2. What is the cost price of the article?
I. The article was sold at a 20% profit and the selling price was Rs 1,800.
II. The profit earned on the article was Rs 300.
Solution:
- I alone: CP × 1.2 = 1,800, so CP = Rs 1,500. Sufficient.
- II alone: profit is Rs 300, but the profit percentage is unknown. Not sufficient.
Answer: (a)
Q9. What is the number of boys in the class?
I. The ratio of boys to girls is 3 : 2 and there are 60 students in total.
II. 40% of the students in the class are girls.
Solution:
- I alone: boys = 3/5 × 60 = 36. Sufficient.
- II alone: boys are 60%, but the total is unknown. Not sufficient.
Answer: (a)
Geometry and Number Based
Q3. What is the area of the rectangle?
I. The length of the rectangle is 7 cm more than its breadth.
II. The perimeter of the rectangle is 34 cm and its length is 12 cm.
Solution:
- I alone: l = b + 7. Two unknowns, one equation. Not sufficient.
- II alone: l + b = 17 and l = 12, so b = 5 and area = 60 cm². Sufficient.
Answer: (b)
Q10. What is the value of the number?
I. 40% of the number is 72.
II. The number is 25% less than 240.
Solution:
- I alone: number = 72 ÷ 0.4 = 180. Sufficient.
- II alone: number = 240 × 0.75 = 180. Sufficient.
Answer: (c)
Speed, Time and Distance Based
Q4. What is the speed of the boat in still water?
I. The downstream speed of the boat is 18 km/h and the speed of the stream is 3 km/h.
II. The upstream speed of the boat is 12 km/h and the speed of the stream is 3 km/h.
Solution:
- I alone: boat = downstream − stream = 18 − 3 = 15 km/h. Sufficient.
- II alone: boat = upstream + stream = 12 + 3 = 15 km/h. Sufficient.
Answer: (c)
Q6. What is the length of the train?
I. The train crosses a 300 m bridge in 24 seconds.
II. The train crosses a pole in 9 seconds at a speed of 72 km/h.
Solution:
- I alone: (L + 300) = 24 × v. Two unknowns (L and v). Not sufficient.
- II alone: 72 km/h = 20 m/s, so L = 20 × 9 = 180 m. Sufficient.
Answer: (b)
Time and Work, Interest and Averages
Q7. In how many days can A alone complete the work?
I. A and B together can complete the work in 12 days.
II. B alone can complete the work in 20 days.
Solution:
- I alone: A’s time depends on B. Not sufficient.
- II alone: says nothing about A. Not sufficient.
- Together: 1/A = 1/12 − 1/20 = 5/60 − 3/60 = 2/60 = 1/30, so A takes 30 days.
Answer: (d)
Q5. What is the average marks of the class?
I. The class has 40 students.
II. The highest marks in the class is 92 and the lowest is 35.
Solution:
- I alone: no marks given. Not sufficient.
- II alone: only the extremes are given. Not sufficient.
- Together: we still do not know the total marks or the distribution. Not sufficient.
Answer: (e)
Q8. What is the simple interest on the sum?
I. The sum is Rs 8,000.
II. The rate of interest is 5% per annum.
Solution: SI = P × R × T / 100, which needs P, R and T.
- Neither statement gives the time period, even when both are combined.
Answer: (e)
Answer Key
| Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Q10 |
|---|---|---|---|---|---|---|---|---|---|
| (d) | (a) | (b) | (c) | (e) | (b) | (d) | (e) | (a) | (c) |
Common Mistakes in Data Sufficiency
- Solving fully and wasting time. You only need to know whether a unique answer exists.
- Using Statement I while checking Statement II. Test each one in isolation first.
- Confusing (c) and (d). (c) means each statement alone works. (d) means you need both together.
- Ignoring units. In Q6, the 72 km/h had to be converted to 20 m/s before getting the length.
- Marking sufficient when two answers are possible. If a statement gives ±8 or two different values, it is not sufficient.
FAQs on Data Sufficiency for Bank Exams
Is data sufficiency asked in IBPS PO Mains?
It has been practiced for Mains-level bank exams, but the exact pattern changes from year to year. Check the latest exam notification and the previous year’s paper to see how it is being asked now.
What is the best trick to solve data sufficiency questions?
Use the elimination method: check Statement I alone, then Statement II alone, and combine them only if both fail. This removes options quickly.
How much time should I spend on one data sufficiency question?
Aim for about 1 minute per question once you are comfortable. Do not calculate the final answer unless you are unsure.
What is the difference between “either I or II” and “both I and II together”?
“Either I or II” means each statement alone gives the answer. “Both together” means neither is enough alone, but combined they are.
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