1
A can finish a work in 10 days and B in 15 days. In how many days can they finish it working together?
Correct answer: A. 6 days
Together they do 1/10 + 1/15 = 1/6 of the work a day, so they need 6 days.
easy
Time and Work, Pipes and Cisterns MCQs
Solved quantitative aptitude MCQs on time and work, efficiency, man-days, wages, alternate-day work, pipes and cisterns and leaks, with worked solutions.
20 MCQsUpdated 27 October 2026
This set covers work done by two or more people, men and women working together, man-days, and pipes and taps that fill or empty a tank.
Take the total work as the LCM of the given times and work in whole units per day or hour; the explanations show this method step by step.
- 2
A, B and C can finish a work alone in 12, 15 and 20 days. How long will they take working together?
Correct answer: B. 5 days
One day's work = 1/12 + 1/15 + 1/20 = (5 + 4 + 3)/60 = 12/60 = 1/5, so together they take 5 days.
medium - 3
A and B together can do a job in 8 days. A alone can do it in 12 days. How long will B alone take?
Correct answer: C. 24 days
B's one day's work = 1/8 − 1/12 = 1/24, so B alone takes 24 days.
medium - 4
A is twice as efficient as B. Together they finish a work in 14 days. How long would A alone take?
Correct answer: D. 21 days
If B does 1 unit a day, A does 2, so together 3 units a day; total work = 3 × 14 = 42 units. A alone: 42 ÷ 2 = 21 days.
medium - 5
15 men can complete a work in 24 days. How many days will 20 men take to complete the same work?
Correct answer: A. 18 days
Total work = 15 × 24 = 360 man-days, so 20 men need 360 ÷ 20 = 18 days.
easy - 6
12 workers can build a road in 30 days. How many workers are needed to build it in 18 days?
Correct answer: B. 20
Total work = 12 × 30 = 360 worker-days; 360 ÷ 18 = 20 workers.
easy - 7
A can do a work in 15 days and B in 20 days. They work together for 6 days, and then A leaves. In how many more days will B finish the work?
Correct answer: C. 6 days
In 6 days they do 6 × (1/15 + 1/20) = 6 × 7/60 = 7/10. The remaining 3/10 takes B 3/10 × 20 = 6 days.
hard - 8
A can do a job in 6 days and B in 12 days. They do it together and are paid ₹4,500. What is A's share?
Correct answer: D. ₹3,000
Wages are shared in the ratio of work done per day, 1/6 : 1/12 = 2 : 1, so A gets 2/3 × 4,500 = ₹3,000.
medium - 9
Pipe A fills a tank in 10 hours and pipe B in 15 hours. If both are opened together, how long will they take to fill it?
Correct answer: A. 6 hours
Together they fill 1/10 + 1/15 = 1/6 of the tank each hour, so 6 hours.
easy - 10
A pipe fills a tank in 4 hours, and an outlet empties the full tank in 6 hours. If both are open, how long will the tank take to fill?
Correct answer: B. 12 hours
Net filling per hour = 1/4 − 1/6 = 1/12, so the tank fills in 12 hours.
medium - 11
Pipes A and B can fill a tank in 12 and 15 hours, and pipe C can empty it in 20 hours. If all three are opened together, how long will the tank take to fill?
Correct answer: C. 10 hours
Per hour: 1/12 + 1/15 − 1/20 = (5 + 4 − 3)/60 = 6/60 = 1/10, so 10 hours.
hard - 12
A pipe can fill a tank in 8 hours, but because of a leak at the bottom it takes 10 hours. How long would the leak take to empty the full tank?
Correct answer: D. 40 hours
Leak rate = 1/8 − 1/10 = 1/40 of the tank per hour, so the leak empties it in 40 hours.
hard - 13
If 6 men or 10 women can do a work in 15 days, in how many days can 3 men and 5 women do it?
Correct answer: A. 15 days
6 men = 10 women, so 3 men = 5 women; 3 men + 5 women = 10 women, who take 15 days.
medium - 14
A can finish a work in 20 days. What fraction of the work will A finish in 5 days?
Correct answer: B. 1/4
In one day A does 1/20 of the work, so in 5 days 5/20 = 1/4 (=0.25).
easy - 15
A can do a work in 8 days and B in 12 days. If they work on alternate days, starting with A, in how many days will the work be finished?
Correct answer: C. 9.5 days
Two days (A then B) = 1/8 + 1/12 = 5/24. After 8 days (4 pairs) 20/24 is done, leaving 4/24 = 1/6. Day 9 is A's: he does 1/8 = 3/24, leaving 1/24, which B finishes in half a day (1/24 ÷ 1/12). Total 9.5 days.
Read detailshard - 16
10 men working 8 hours a day finish a job in 12 days. How many days will 8 men take working 10 hours a day?
Correct answer: D. 12 days
Total = 10 × 8 × 12 = 960 man-hours; 8 men × 10 hours = 80 man-hours a day, so 960 ÷ 80 = 12 days.
medium - 17
A tap can fill a tank in 30 minutes. How long will it take to fill the tank when it is already one-third full?
Correct answer: A. 20 minutes
Two-thirds of the tank is still empty: 2/3 × 30 = 20 minutes.
easy - 18
A and B can do a work in 12 and 24 days. They work together for 4 days, and then C, who can do it alone in 24 days, joins them. How many more days will the three take to finish it?
Correct answer: B. 3 days
In 4 days A and B do 4 × (1/12 + 1/24) = 4 × 1/8 = 1/2. The remaining 1/2 at 1/12 + 1/24 + 1/24 = 1/6 per day takes 1/2 ÷ 1/6 = 3 days.
Read detailshard - 19
Two outlet pipes can empty a full tank in 20 and 30 minutes. How long will they take to empty it together?
Correct answer: C. 12 minutes
Together: 1/20 + 1/30 = 1/12 of the tank per minute, so 12 minutes.
easy - 20
A takes 18 days to finish a work. B is 50% more efficient than A. How many days will B take to finish the same work?
Correct answer: D. 12 days
B does 1.5 times as much work a day as A, so B takes 18 ÷ 1.5 = 12 days.
medium