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25 outlets working 6 hours a day, can empty a reservoir in 10 days. If only 15 outlets are operational and work for 4 hours a day, in how many days the reservoir can be emptied?

A.

20 days

B.

18 days

C.

25 days

D.

22 days

Answer with explanation

Answer: Option CExplanation

Apply formula used in work and time problems; M1D1T1W2 = M2D2T2W1

M1= 25 outlets, D1=10 days, T1= 6 hours/day, W2 = to fill the reservoir

M2= 15 outlets, D2=? T2 = 4 hours/day, W1= to fill the reservoir

W1=W2

So we have; M1D1T1= M2D2T2

25*10*6=15*D2*4

1500 = 60 * D2

D2=1500/60=25 days

Workspace

Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank?

A.

10 min. 20 sec.

B.

11 min. 45 sec.

C.

12 min. 30 sec.

D.

14 min. 40 sec.

Answer with explanation

Answer: Option DExplanation

Workspace

A tank is filled in eight hours by three pipes A, B and C. Pipe A is twice as fast as pipe B, and B is twice as fast as C. How much time will pipe B alone take to fill the tank?

A.

24 hrs

B.

28 hrs

C.

32 hrs

D.

36 hrs

Answer with explanation

Answer: Option BExplanation

Explanation:

1/A + 1/B + 1/C = 1/8 (Given)

Also given that A = 2B and B = 2C

=> 1/2B + 1/B + 2/B = 1/8

=> (1 + 2 + 4)/2B = 1/8

=> 2B/7 = 8

=> B = 28 hours.

Workspace

A cistern has three pipes, A, B and C. The pipes A and B can fill it in 4 and 5 hours respectively and C can empty it in 2 hours. If the pipes are opened in order at 1, 2 and 3 A.M. When will the cistern be empty?

A.

3 PM

B.

4 PM

C.

5 PM

D.

7 PM

Answer with explanation

Answer: Option CExplanation

So let us consider the fraction of cistern filled by each pipe in one hour:—

Pipe A: 1/4 in one hour

Pipe B: 1/5 in one hour

Pipe C: -1/2 in one hour

To make calculations easier, let us take the LCM of the above fractions and so we get-

Pipe A: 5/20 per hour

Pipe B: 4/20 per hour

Pipe C: -10/20 per hour

So Pipe A is opened at 1 am, thus the amount of water filled till 2 am is: 5/20

Pipe B is open at 2 am, so Pipe A & B both fill the tank right now, so the amount filled now is:

5/20 + (5/20 + 4/20) = 14/20

At 3 am all the pipes are opened, thus water-filled till 4 am is:—

= 14/20 + (5/20 + 4/20 — 10/20)

= 14/20 — 1/20

=13/20

Now every consecutive hour, -1/20 of the tank will be emptied as seen above.

So after 4 am, 13 more hours are required to empty the tank.

Thus the cistern will be emptied at 5 pm in the evening.

Workspace

Two pipes function simultaneously the reservoir will be filled in 12 hours. One pipe fills reservoir 10 hours faster than the other. How many hours does the faster pipe take to fill the reservoir?

A.

25 hrs

B.

20 hrs

C.

28 hrs

D.

35 hrs

Answer with explanation

Answer: Option BExplanation

1/x + 1/(x + 10) = 1/12

x = 20

Workspace

Two pipes A and B can separately fill a tank in 12 and 15 minutes respectively. A third pipe C can drain off 45 liters of water per minute. If all the pipes are opened, the tank can be filled in 15 minutes. What is the capacity of the tank

A.

480 liters

B.

540 liters

C.

600 liters

D.

675 liters

Answer with explanation

Answer: Option BExplanation

1/12 + 1/15 – 1/x = 1/15

x = 12

12 * 45 = 540

Workspace

3 pipes when opened for 3 hours can fill 3 buckets. How many buckets can 2 pipes open for 2 hours approximately fill?

A.

2/3 bucket

B.

4/3 bucket

C.

2 buckets

D.

1 bucket

Answer with explanation

Answer: Option BExplanation

2 pipes open for 2 hours will fill = (2/3) x (2/3) x 3 = 4/3 buckets

Workspace

A.

2/3 buckets

B.

2 buckets

C.

1 bucket

D.

4/3 bucket

Answer with explanation

Answer: Option DExplanation

2 pipes open for 2 hours will fill = (2/3) x (2/3) x 3 = 4/3 buckets

Workspace

A water tank is 2/5 th full. Inlet A can fill the tank in 10 minutes while an outlet pipe B can empty it in 6minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?

A.

It empty in 6 min

B.

It empties in 4.8 mins

C.

It empties in 5.6 min

D.

*I*t fills in 5.6 min

Answer with explanation

Answer: Option AExplanation

Workspace

One fill pipe A is 3 times faster than second fill pipe B and takes 32 minutes less than the fill pipe B. When will the cistern be full if both pipes are opened together?

A.

12 min

B.

6 min

C.

10 min

D.

8 min

Answer with explanation

Answer: Option AExplanation

Let pipe A takes p min to fill

Then,

pipe B takes 3p min to fill

=> 3p – p = 32

=> p = 16 min => 3p = 48 min

Required, both pipes to fill = (48 x 16)/(48 + 16) min = 12 min.

Workspace

A Tank is normally filled in 9 hours but takes four hours longer to fill because of a leak in its bottom. If the tank is full, the leak will empty it in ?

A.

32.5 hrs

B.

29.25 hrs

C.

30.30 hrs

D.

31 hrs

Answer with explanation

Answer: Option BExplanation

Let the leak will empty the tank in x hrs

Then, 1/9 – 1/x = 1/13

x = 29.25 hrs

Workspace

A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half ?

A.

31 mins

B.

29 mins

C.

28 mins

D.

30 mins

Answer with explanation

Answer: Option DExplanation

Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24

Suppose the tank is filled in x minutes.

Then, x/2(1/24 + 1/40) = 1

(x/2) * (1/15) = 1 => x = 30 min.

Workspace

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