Time and Work | Aptitude Questions and Answers | Aptitude Free Online-Tests | LucentBlackBoard

01.

A and B can do a job together in 7 days. A is 1 3/4 times as efficient as B. The same job can be done by A alone in :

A.	9 1/3 days	B.	11 days
C.	12 1/4 days	D.	16 1/3 days

Answer and Explanation

Answer: 11 days

Explanation:

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02.

Twenty women can do a work in sixteen days. Sixteen men can complete the same work in fifteen days. What is the ratio between the capacity of a man and a woman?

A.	3 : 4	B.	4 : 3
C.	5 : 3	D.	Data inadequate

Answer and Explanation

Answer: 4 : 3

Explanation:

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03.

A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?

A.	11 days	B.	13 days
C.	20 3/17 days	D.	None of these

Answer and Explanation

Answer: 13 days

Explanation:

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04.

P can complete a work in 12 days working 8 hours a day. Q can complete the same work in 8 days working 10 hours a day. If both P and Q work together, working 8 hours a day, in how many days can they complete the work?

A.	5 5/11	B.	5 6/11
C.	6 5/11	D.	6 6/11

Answer and Explanation

Answer: 5 5/11

Explanation:

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05.

If 6 men and 8 boys can do a piece of work in 10 days while 26 men and 48 boys can do the same in 2 days, the time taken by 15 men and 20 boys in doing the same type of work will be:

A.	4 days	B.	5 days
C.	6 days	D.	7 days

Answer and Explanation

Answer: 4 days

Explanation:

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06.

If X and Y complete a certain work in 10 days, Y and Z in 16 days and X and Z in 22 days, find the time required for each one to complete the work while working separately.

A.	120, 40, 60 days	B.	120, 60, 80 days
C.	40, 30, 120 days	D.	30, 40, 60 days

Answer and Explanation

Answer: 120, 40, 60 days

Explanation:
Let a: be the time in which X & Y completes their work = 30 days
b: time in which Y & Z completes their work = 24 days
c: time in which X & Z completes their work = 40 days
X alone can complete the work in (2 * a * c) / (ab + bc – ac) days
= 2 * 30 * 24 * 40 / ((30 * 24) + (24 * 40) – (30 * 40)) = 120 days
Y alone can complete the work in 2 * a * b * c / (- ab + bc + ac) days
= 2 * 30 * 24 * 40 / (-(30 * 24) + (24 * 40) + (30 * 40)) = 40 days
Z alone can complete the work in 2 * a * b * c / (ab – bc + ac) days
= 2 * 30 * 24 * 40 / ((30 * 24) – (24 * 40) + (30 * 40))
= 60 days

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07.

If 6 men working together can complete 50 identical tasks in 4 hours then how many such identical tasks can be completed if 10 men are working together for 6 hours?

A.	20	B.	125
C.	100	D.	60

Answer and Explanation

Answer: 125

Explanation:
M1*D1*W2 = M2*D2*W1
Where, M – number of people working
D – time of work
W – number of tasks or work
6*4*W2 = 10*6*50
W2 = 125 tasks

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08.

A cistern can be filled by two pipes A and B in 30 and 36 minutes respectively. When the cistern is empty, both the pipes are opened for a certain time, but being partially clogged, only 5/6 of the full quantity of water flows through the pipe A and only 9/10 through the pipe B. the obstructions, however, being suddenly removed, the cistern is filled in 15 1/12 minutes from that moment. How long was it before the full flow of water began?

A.	1 min	B.	2 min
C.	1 ½ min	D.	2 ½ min

Answer and Explanation

Answer: 1 min

Explanation:
Let the pipes A and B be open for x minutes before the full flow began.
x (5 /(6×30) + 9 / (10×36)) + 31/2(1/30 + 1/36) = 1
x(1/36 + 1/40) + 31/2(1/30 + 1/36) =1
x(19/360) + 31/2(11/180) = 1
19x + 341 / 360 = 1
19x = 360 – 341 =19
x = 19/19
x = 1 min

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09.

Two taps A and B can separately fill a cistern in 10 and 12 min respectively. If the emptying tap C is open, then the two filling taps can together fill the cistern in 15 minutes. When the cistern is full, how long will it take for the tap C alone to empty the cistern?

A.	8×4/7 min	B.	7 × ½ min
C.	10 min	D.	12 min

Answer and Explanation

Answer: 8×4/7 min

Explanation:
Let the tap alone C take x minutes to empty the cistern, then
1/x = 1/10 + 1/12 – 1/15 = 6 + 5 – 4/ 60 = 7/60
x = 60/7 min, i.e. 8 × 4/7 min

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10.

A can do a piece of work in 45 days. He works at it for 5 days and then B completes it in 20 days. How long will A and B together take to complete the work?

A.	14 × 1/3 days	B.	15 days
C.	13 × 1/3 days	D.	14 days

Answer and Explanation

Answer: 15 days

Explanation:
Explanation: In one day A does 1/45 of the work.
In 5 days A does 5/45 = 1/9 of the work
Remaining part of the work = 1 – 1/9= 8/9
B takes 20 days to do 8/9 of the work.
In one day B will do 8 / 9×20 = 2/45 of the work
Working together ( A & B ) will complete 1/45 + 2/45
= 3/45 = 1/15 of the work
They will take 45/3 days, i.e. 15 days

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