WORK-TIME AND UNITARY METHOD (CDS)

Total Questions: 53

41. Pipe A can fill a tank in 10 min and pipe B can empty it in 15 min. If both the pipes are opened in an empty tank, then the time taken to make it full is [2014 (I) Morning Shift]

Correct Answer: (c) 30 min
Solution:Part filled by pipe A in 1 min = 1/10

42. X can complete a job in 12 days. If X and Y work together, they can complete the job in 6⅔ days. Y alone can complete the job in [2014 (I) Morning Shift]

Correct Answer: (c) 15 days
Solution:X’s one day’s work = 1/12

43. A mason can build a tank in 12 h. After working for 6 h, he took the help of a boy and finished the work in another 5h. The time that the boy will take alone to complete the work is [2014 (I) Morning Shift]

Correct Answer: (c) 60 h
Solution:Mason work for 1h = 1/12


44. If 3 men and 4 boys can do a piece of work in 8 days, then 6 men and 8 boys can do the same work in [2014 (I) Morning Shift]

Correct Answer: (b) 4 days
Solution:3 men + 4 boys = 8 days, 6 men + 5 boys= ?

45. X can do a piece of work in 25 day. Y is 25% more efficient than X. The number of day taken by Y is [2014 (I) Morning Shift]

Correct Answer: (b) 20 days
Solution:


46. 45 people take 18 day to dig a pond. If the pond would have to be dug in 15 days, then the number of people to be employed will be [2014 (I) Morning Shift]

Correct Answer: (b) 54
Solution:


47. A and B can do a piece of work in 10 h. B and C can do it in 15 h, while A and C take 12 h to complete the work. B independently can complete the work in [2014 (I) Morning Shift]

Correct Answer: (d) 24 h
Solution:A’s and B’s 1 h’s work = 1/10

48. There are two taps A and B to fill up a water tank. The tank can be filled in 40 min, if both taps are on. The same tank can be filled in 60 min, if tap A alone is on. How much time will tap B alone take, to fill up the same tank? [2014 (I) Morning Shift]

Correct Answer: (d) 120 min
Solution:

49. A stock of food is enough for 240 men for 48 days. How long will the same stock last for 160 men? [2014 (I) Morning Shift]

Correct Answer: (d) 72 days
Solution:Here, M₁ = 240, D₁ = 48

50. A can do a piece of work in ‘x ’ day and B can do the same work 3x days. To finish the work together they take 12 days. What is the value of ‘x’? [2014 (I) Morning Shift]

Correct Answer: (d) 16
Solution:1 day’s work of A = 1/x