Preparation guide
ISRO Aptitude Questions
Overview
This page has ISRO aptitude questions with full solutions - numerical ability, verbal, and logical reasoning - in the style students report for the ISRO Online Assessment. Start with the timed mock quiz, then work the solved set and log every miss by topic.
ISRO Aptitude Mock Quiz
Timed placement-style MCQs with score and explanations after you submit. Use it to check speed and accuracy before the real test.
Questions15
Time10 min
Reasoning
Find the next number: 2, 6, 12, 20, 30, ?
Differences +4, +6, +8, +10, +12 → next is 42.
Quantitative
In what ratio should water be mixed with milk costing ₹20 per liter to get a mixture worth ₹15 per liter?
Correct answer: 1:3
Quantitative
Problem: If A:B = 2:3 and B:C = 4:5, find A:B:C.
A:B = 2:3 = 8:12 (multiply by 4) B:C = 4:5 = 12:15 (multiply by 3) A:B:C = 8:12:15
Reasoning
Odd one out: 8, 27, 64, 100, 125
Others are perfect cubes; 100 is not.
Quantitative
If the word TRADE is coded as XVEHI, then how the word PUBLIC should be coded?
Correct answer: TYFPMG
Reasoning
Statements: All engineers are professionals. Some professionals are managers. Conclusions: I. Some engineers are managers. II. All managers are engineers.
Analyzing the statements: - All engineers are professionals (A → B) - Some professionals are managers (B → C, some) Conclusion I: Some engineers are managers - Since all engineers are professionals, and some professionals are managers, we can say some engineer
Verbal
Antonym of "Benevolent":
Benevolent ↔ malevolent.
Verbal
There are two pipes in a tank. Pipe A is for filling the tank and pipe B is for emptying the tank. If A can fill the tank in 10 hours and B can empty the tank in 15 hours then find how many hours will it take to completely fill a half empty tank?
Correct answer: 15 hours
Reasoning
Number Series - 37, 47, 58, ?, 79, 95
Correct answer: 70
Verbal
One who loves books is a:
Bibliophile = lover of books.
Quantitative
Six people A, B, C, D, E, F are sitting around a circular table. A is opposite to D. B is between A and C. E is not adjacent to A. Who is sitting opposite to E?
In circular arrangement with 6 people, opposite pairs are: (A,D), (B,E), (C,F) Since A is opposite D, and B is between A and C, and E is not adjacent to A E must be opposite B
Quantitative
Identify the next shape in the sequence: Circle, Square, Triangle, Circle, Square, ?
The sequence repeats every three shapes: Circle, Square, Triangle After Circle and Square, the next shape is Triangle
Verbal
Antonym of "Optimistic":
Optimistic ↔ pessimistic.
Reasoning
If in a certain code, FLOOR is written as EKNQQ, how is TABLE written?
Each letter −1: T→S, A→Z, B→A, L→K, E→D → SZAKD.
Quantitative
A and B invest ₹5,000 and ₹7,000 respectively in a business. After 6 months, A withdraws ₹2,000. If the profit at the end of the year is ₹4,500, find B's share.
A's investment: 5000 × 6 + 3000 × 6 = 30,000 + 18,000 = 48,000 B's investment: 7000 × 12 = 84,000 Ratio = 48,000 : 84,000 = 4 : 7 B's share = 7/(4+7) × 4500 = 7/11 × 4500 = ₹2,863.64
Your score
0/15(0%)
Review
ISRO aptitude topics students usually practice
- Numerical / quantitative: percentages, profit and loss, ratios, time and work, averages, SI/CI, speed-distance
- Logical reasoning: series, coding-decoding, blood relations, seating, syllogisms
- Verbal ability: grammar, vocabulary, error spotting, idioms
Numerical ability questions
Q1: Fraction simplify
Problem: Simplify: (3/4) ÷ (9/8) × (2/3).
Solution: (3/4) × (8/9) × (2/3) = (3×8×2)/(4×9×3) = 48/108 = 4/9.
Answer: 4/9
Q2: Marked price discount
Problem: A shopkeeper marks goods 20% above cost and then gives a 10% discount. What is the profit percentage?
Solution: Let CP = ₹100. Marked price = ₹120. Discount = 10% of 120 = ₹12. SP = 120 − 12 = ₹108. Profit % = 8%.
Answer: 8%
Q3: Worker scaling
Problem: Eight workers finish a job in 10 days. How many days will 10 workers take for the same job (same pace)?
Solution: Total man-days = 8 × 10 = 80. Days for 10 workers = 80 / 10 = 8 days.
Answer: 8 days
Q4: LCM HCF product
Problem: Two numbers have HCF 12 and LCM 180. If one number is 36, find the other.
Solution: Product of numbers = HCF × LCM. 36 × other = 12 × 180 = 2160. Other = 2160 / 36 = 60.
Answer: 60
Q5: Number digit sum
Problem: Sum of digits of a two-digit number is 9. If digits are reversed, number increases by 27. Original number?
Solution: 10a+b; a+b=9; 10b+a = 10a+b+27 → 9b−9a=27 → b−a=3. a+b=9, b−a=3 → b=6, a=3. Number = 36.
Answer: 36
Q6: Profit on a pen
Problem: If the cost price of a pen is ₹40 and it is sold at a 25% profit, what is the selling price?
Solution: Profit = 25% of 40 = ₹10. Selling price = 40 + 10 = ₹50.
Or SP = CP × 1.25 = 40 × 1.25 = ₹50.
Answer: ₹50
Q7: Net percent change
Problem: A number is increased by 20% and then decreased by 20%. What is the net percentage change?
Solution: Start with 100 → 120 → 96. Net change = 4% decrease. Formula: successive +a then −a gives −(a²/100)% = −4%.
Answer: 4% decrease
Q8: Ratio mixture tea
Problem: Tea worth ₹120/kg is mixed with tea worth ₹180/kg in the ratio 3:2. Find the price of the mixture per kg.
Solution: Price = (3×120 + 2×180) / 5 = (360 + 360) / 5 = 720/5 = ₹144 per kg.
Answer: ₹144
Q9: Percentage of percentage
Problem: What is 15% of 20% of 400?
Solution: 20% of 400 = 80. 15% of 80 = 12.
Answer: 12
Q10: Geometry triangle
Problem: A right triangle has legs 6 and 8. Hypotenuse?
Solution: √(36+64)=√100=10.
Answer: 10
Verbal ability questions
Q11: Synonym - abundant
Problem: Choose the best synonym of ‘abundant’.
Solution: ‘Abundant’ means present in large quantity. Closest match: plentiful.
Answer: Plentiful
Q12: One word - extinct
Problem: A species that no longer exists is?
Solution: Extinct.
Answer: Extinct
Q13: Antonym - scarce
Problem: Choose the best antonym of ‘scarce’.
Solution: ‘Scarce’ means in short supply. Opposite: abundant.
Answer: Abundant
Q14: Fill in the blank
Problem: She _____ to the office every day by metro. (go / goes / going / gone)
Solution: Third-person singular present needs ‘goes’.
Answer: goes
Q15: Sentence rearrange
Problem: Arrange: (1) the exam (2) she cleared (3) with ease
Solution: She cleared the exam with ease.
Answer: 2-1-3
Q16: Idiom - hit the nail
Problem: What does ‘hit the nail on the head’ mean?
Solution: To describe exactly the right point.
Answer: Be exactly right
Reasoning ability questions
Q17: Direction turn
Problem: A person walks 5 km north, then 3 km east, then 5 km south. How far is he from the start, and in which direction?
Solution: North 5 and south 5 cancel. He is 3 km east of the start.
Answer: 3 km east
Q18: Coding opposite
Problem: If ROAD is coded as URDG, how is RACE coded?
Solution: Each letter +3: R→U, O→R, A→D, D→G. R→U, A→D, C→F, E→H → UDFH.
Answer: UDFH
Q19: Analogy tool
Problem: Hammer is to Nail as Pen is to ?
Solution: Hammer drives nail; pen writes (on paper/ink). Best: Paper / Writing.
Answer: Paper
Q20: Mirror clock
Problem: A clock shows 3:15. What is the mirror image time approximately (12-hour mirror)?
Solution: Mirror of h:m is roughly 12:00 − 3:15 → 8:45.
Answer: 8:45
Q21: Odd one out
Problem: Find the odd one out: 3, 5, 7, 9, 11
Solution: 3, 5, 7, and 11 are prime. 9 = 3×3 is composite, so it is the odd one out.
Answer: 9
Q22: Series multiply
Problem: Find the next number: 3, 9, 27, 81, ?
Solution: Each term is multiplied by 3. Next = 81 × 3 = 243.
Answer: 243
Timed practice tips for ISRO
- First pass: only high-confidence questions
- Mark and skip time sinks early
- Keep verbal accuracy high - these are easy marks if you stay calm
- Run the mock quiz at least three times a week under real timing
- Sleep properly the night before; fatigue hurts DI and calculation accuracy