Q4. An article is sold at a loss of 10%. Had it been sold for ₹110 more, there would have been a gain of 10%. Find the cost price (in ₹).
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Answer: A. 550
10% + 10% = 20% of CP = ₹110, so CP = 110 × 100/20 = ₹550.
Profit and Loss · hard
Q5. The population of a town is 40000. It increases by 5% every year. What will the population be after 2 years?
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Answer: B. 44100
40000 × (105/100)^2 = 44100.
Percentage · medium
Q6. Find the compound interest on ₹32000 for 1 year at 20% per annum, compounded half-yearly (in ₹).
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Answer: B. 6720
Rate = 10% per half-year for 2 periods. A = 32000 × (110/100)² = ₹38720; CI = ₹6720.
Compound Interest · hard
Q7. Two cities are 150 km apart. Two cars start at the same time from the two cities towards each other at 35 km/h and 25 km/h. After how many hours will they meet?
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Answer: D. 2.5 hours
Time = 150/(35 + 25) = 2.5 hours.
Speed, Time and Distance · medium
Q8. In how many years will a sum of money become three times itself at 5% per annum simple interest?
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Answer: C. 40 years
SI = 2P, so 2P = P × 5 × T / 100, giving T = 200/5 = 40 years.
Simple Interest · hard
Q9. A batsman has an average of 39 runs after 17 innings. How many runs must he score in the next innings to raise his average by 2?
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Answer: B. 75
New total = 18 × 41 = 738; old total = 17 × 39 = 663. Runs = 75.
Average · hard
Q10. A boat goes downstream at 25 km/h and upstream at 21 km/h. What is the speed of the stream?
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Answer: B. 2 km/h
(25 − 21)/2 = 2 km/h.
Boats and Streams · medium
Q11. What is the difference between compound interest and simple interest on ₹37500 for 2 years at 4% per annum (in ₹)?
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Answer: C. 60
CI − SI = 37500 × (4/100)² = ₹60.
Compound Interest · hard
Q12. The present ages of A and B are in the ratio 2:7. After 6 years, their ages will be in the ratio 1:2. What is A's present age?
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Answer: A. 4 years
2(2x + 6) = 1(7x + 6) ⇒ x = 2. A's age = 2 × 2 = 4 years.
Problems on Ages · hard
Q13. A, B and C can do a work alone in 6, 10 and 15 days respectively. How many days will they take working together?
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Answer: D. 3 days
1/6 + 1/10 + 1/15 = 1/3. So they need 3 days.
Time and Work · medium
Q14. The average of 7 consecutive even numbers is 50. What is the largest of these numbers?
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Answer: B. 56
The middle (4th) number is 50. The largest is 3 steps of 2 above it: 50 + 6 = 56.
Average · medium
Q15. A, B and C can do a work alone in 10, 15 and 30 days respectively. How many days will they take working together?
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Answer: B. 5 days
1/10 + 1/15 + 1/30 = 1/5. So they need 5 days.
Time and Work · medium
Q16. If tan θ = 5/12 (θ acute), find cos θ.
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Answer: D. 12/13
Hypotenuse = √(5² + 12²) = 13. cos θ = 12/13.
Trigonometry · hard
Q17. Find the mean proportional between 36 and 48.
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Answer: A. 12
√(36 × 48) = √1728 = 12.
Ratio and Proportion · medium
Q18. Two trains of lengths 150 m and 130 m run in the same direction at 36 km/h and 45 km/h. How long will they take to cross each other completely?
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Answer: A. 112 seconds
Relative speed = 9 km/h = 2.5 m/s. Time = (150 + 130)/2.5 = 112 s.
Speed, Time and Distance · hard
Q19. A batsman has an average of 39 runs after 19 innings. How many runs must he score in the next innings to raise his average by 3?
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Answer: D. 99
New total = 20 × 42 = 840; old total = 19 × 39 = 741. Runs = 99.
Average · hard
Q20. Two cities are 480 km apart. Two cars start at the same time from the two cities towards each other at 51 km/h and 29 km/h. After how many hours will they meet?
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Answer: B. 6 hours
Time = 480/(51 + 29) = 6 hours.
Speed, Time and Distance · medium
Q21. Find the total surface area of a cuboid of length 6 cm, breadth 10 cm and height 5 cm.
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Answer: C. 280 cm²
2(60 + 50 + 30) = 280 cm².
Mensuration · medium
Q22. An article is sold at a loss of 4%. Had it been sold for ₹240 more, there would have been a gain of 6%. Find the cost price (in ₹).
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Answer: C. 2400
4% + 6% = 10% of CP = ₹240, so CP = 240 × 100/10 = ₹2400.
Profit and Loss · hard
Q23. The HCF of two numbers is 7 and their LCM is 70. If one of the numbers is 14, find the other.