1. A father is 40 and his son is 10. In how many years will the father be twice as old as the son?
- 30 years
- 10 years
- 20 years
- 25 years
Answer: C) 20 years
Explanation: 40 + x = 2(10 + x) Rightarrow x = 40 - 20 = 20.
MCQs / Quantitative Reasoning / Speed, Time, Work & Ages
Speed, Time, Work & Ages MCQs — Quantitative Reasoning
34 multiple-choice questions on Speed, Time, Work & Ages from Quantitative Reasoning, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.
2. Pipe A fills a tank in 2 hours; pipe B empties it in 6 hours. If both are open, how long to fill the tank?
- 3 hours
- 4 hours
- 1.5 hours
- 5 hours
Answer: A) 3 hours
Explanation: Net filling per hour = tfrac12 - tfrac16 = tfrac412, so time = 3 hours.
3. A can do a job in 10 days and B in 15 days. Working together, how many days will they take?
- 5 days
- 8 days
- 12 days
- 6 days
Answer: D) 6 days
Explanation: In one day they do tfrac110 + tfrac115 = tfrac25150 of the job, so time = tfrac15025 = 6 days.
4. A man drives to a town at 40 km/h and returns by the same road at 60 km/h. His average speed for the whole journey is:
- 52 km/h
- 44 km/h
- 48 km/h
- 50 km/h
Answer: C) 48 km/h
Explanation: For equal distances, average speed = dfrac2xyx+y = dfrac2 40 60100 = 48 km/h (not the simple average 50).
5. 12 workers can finish a wall in 10 days. How many days will 8 workers take?
- 15 days
- 13 days
- 6 days
- 17 days
Answer: A) 15 days
Explanation: Total work = 12 10 = 120 worker-days; 120 div 8 = 15 days.
6. A train 200 m long runs at 72 km/h. How long does it take to pass a pole?
- 14 s
- 7 s
- 20 s
- 10 s
Answer: D) 10 s
Explanation: Speed = 72 tfrac518 = 20 m/s; time = 200 div 20 = 10 s.
7. Convert 54 km/h into m/s.
- 20 m/s
- 12 m/s
- 15 m/s
- 194 m/s
Answer: C) 15 m/s
Explanation: Multiply by tfrac518: 54 tfrac518 = 15 m/s.
8. A can do a job in 18 days and B in 9 days. Working together, how many days will they take?
- 13 days
- 6 days
- 8 days
- 9 days
Answer: B) 6 days
Explanation: In one day they do tfrac118 + tfrac19 = tfrac27162 of the job, so time = tfrac16227 = 6 days.
9. A car covers 240 km in 4 hours. At the same speed, how far will it go in 7 hours?
- 360 km
- 480 km
- 420 km
- 400 km
Answer: C) 420 km
Explanation: Speed = 240 div 4 = 60 km/h; 60 7 = 420 km.
10. Convert 72 km/h into m/s.
- 259 m/s
- 25 m/s
- 17 m/s
- 20 m/s
Answer: D) 20 m/s
Explanation: Multiply by tfrac518: 72 tfrac518 = 20 m/s.
11. The present ages of two brothers add up to 50 years, and 5 years ago their ages were in the ratio 3:2. What is the elder one's present age?
- 21 years
- 29 years
- 34 years
- 24 years
Answer: B) 29 years
Explanation: Let ages 5 years ago be 3x and 2x. Then 5x + 10 = 50, so x = 8. Elder now = 3 8 + 5 = 29.
12. A is twice as old as B. Ten years ago A was three times as old as B. What is B's present age?
- 30 years
- 20 years
- 15 years
- 10 years
Answer: B) 20 years
Explanation: A = 2B and A - 10 = 3(B - 10) → 2B - 10 = 3B - 30 → B = 20.
13. A 150 m train at 72 km/h crosses a 250 m long platform. Time taken?
- 12 s
- 7 s
- 20 s
- 25 s
Answer: C) 20 s
Explanation: Distance = 150 + 250 = 400 m; speed = 20 m/s; time = 400 div 20 = 20 s.
14. A father is 36 and his son is 12. In how many years will the father be twice as old as the son?
- 14 years
- 17 years
- 12 years
- 22 years
Answer: C) 12 years
Explanation: 36 + x = 2(12 + x) Rightarrow x = 36 - 24 = 12.
15. Pipe A fills a tank in 3 hours; pipe B empties it in 6 hours. If both are open, how long to fill the tank?
- 8 hours
- 3 hours
- 6 hours
- 2 hours
Answer: C) 6 hours
Explanation: Net filling per hour = tfrac13 - tfrac16 = tfrac318, so time = 6 hours.
16. Two cars start 300 km apart and drive towards each other at 40 km/h and 60 km/h. After how many hours do they meet?
- 4 h
- 6 h
- 3 h
- 15 h
Answer: C) 3 h
Explanation: Moving towards each other, speeds add: 40+60 = 100 km/h. Time = 300 div 100 = 3 h.
17. A man drives to a town at 20 km/h and returns by the same road at 30 km/h. His average speed for the whole journey is:
- 20 km/h
- 28 km/h
- 24 km/h
- 25 km/h
Answer: C) 24 km/h
Explanation: For equal distances, average speed = dfrac2xyx+y = dfrac2 20 3050 = 24 km/h (not the simple average 25).
18. Convert 108 km/h into m/s.
- 30 m/s
- 35 m/s
- 388 m/s
- 27 m/s
Answer: A) 30 m/s
Explanation: Multiply by tfrac518: 108 tfrac518 = 30 m/s.
19. A can do a job in 12 days and B in 24 days. Working together, how many days will they take?
- 12 days
- 18 days
- 10 days
- 8 days
Answer: D) 8 days
Explanation: In one day they do tfrac112 + tfrac124 = tfrac36288 of the job, so time = tfrac28836 = 8 days.
20. Convert 90 km/h into m/s.
- 25 m/s
- 22 m/s
- 30 m/s
- 324 m/s
Answer: A) 25 m/s
Explanation: Multiply by tfrac518: 90 tfrac518 = 25 m/s.
21. Two cars start 180 km apart and drive towards each other at 25 km/h and 35 km/h. After how many hours do they meet?
- 3 h
- 18 h
- 6 h
- 4 h
Answer: A) 3 h
Explanation: Moving towards each other, speeds add: 25+35 = 60 km/h. Time = 180 div 60 = 3 h.
22. Convert 36 km/h into m/s.
- 10 m/s
- 7 m/s
- 15 m/s
- 129 m/s
Answer: A) 10 m/s
Explanation: Multiply by tfrac518: 36 tfrac518 = 10 m/s.
23. A train 150 m long runs at 54 km/h. How long does it take to pass a pole?
- 7 s
- 20 s
- 14 s
- 10 s
Answer: D) 10 s
Explanation: Speed = 54 tfrac518 = 15 m/s; time = 150 div 15 = 10 s.
24. 15 workers can finish a wall in 8 days. How many days will 20 workers take?
- 4 days
- 6 days
- 10 days
- 8 days
Answer: B) 6 days
Explanation: Total work = 15 8 = 120 worker-days; 120 div 20 = 6 days.
25. 6 workers can finish a wall in 20 days. How many days will 10 workers take?
- 14 days
- 12 days
- 10 days
- 33 days
Answer: B) 12 days
Explanation: Total work = 6 20 = 120 worker-days; 120 div 10 = 12 days.
Page 1 of 2 Next
Practise Speed, Time, Work & Ages MCQs