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Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?

A.

60 gallons

B.

100 gallons

C.

120 gallons

D.

180 gallons

Answer with explanation

Answer: Option CExplanation

Work done by the waste pipe in 1 minute = 1/15 – (1/20 + 1/24) = – 1/40

Volume of 1/40 part = 3 gallons\

Volume of whole = 3 * 40 = 120 gallons.

Workspace

A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?

A.

20 hrs

B.

25 hrs

C.

35 hrs

D.

Cannot be determined

Answer with explanation

Answer: Option CExplanation

Suppose pipe A alone takes x hours to fill the tank.

Then, pipes B and C will take x/2 and x/4 hours respectively to fill the tank.

1/x + 2/x + 4/x = 1/5

7/x = 1/5 => x = 35 hrs.

Workspace

A.

90 min

B.

100 min

C.

110 min

D.

120 min

Answer with explanation

Answer: Option BExplanation

Work done by the third pipe in 1 min = 1/50 – (1/60 + 1/75) = – 1/100.

[-ve sign means emptying]

The third pipe alone can empty the cistern in 100 min.

Workspace

A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?

A.

4.5 hrs

B.

5 hrs

C.

6.5 hrs

D.

7.2 hrs

Answer with explanation

Answer: Option DExplanation

Net part filled in 1 hour = (1/4 – 1/9) = 5/36

The cistern will be filled in 36/5 hrs i.e., 7.2 hrs.

Workspace

Two pipes can fill a tank in 18 minutes and 15 minutes. An outlet pipe can empty the tank in 45 minutes. If all the pipes are opened when the tank is empty, then how many minutes will it take to fill the tank?

A.

12

B.

13

C.

11

D.

10

Answer with explanation

Answer: Option DExplanation

Part of the filled by all the three pipes in one minute

= 1/18 + 1/15 – 1/45 = (5 + 6 – 2)/90 = 9/90 = 1/10

So, the tank becomes full in 10 minutes.

Workspace

A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 28 minutes. When both pipes are opened, find when the cistern will be full?

A.

60 min

B.

80 min

C.

70 min

D.

48 min

Answer with explanation

Answer: Option CExplanation

1/20 – 1/28 = 1/70

70 minutes

Workspace

A.

7 min

B.

8 min

C.

9 min

D.

10 min

Answer with explanation

Answer: Option BExplanation

1/10 + 1/15 = 1/6 * 4 = 2/3

1 – 2/3 = 1/3

1/10 + 1/15 – 1/x = 1/3

x = 8

Workspace

A cistern is normally filled in 8 hours but takes two hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty it in?

A.

16 hrs

B.

20 hrs

C.

40 hrs

D.

25 hrs

Answer with explanation

Answer: Option CExplanation

1/8 – 1/x = 1/10

x = 40

Workspace

Two pipes A and B can separately fill a tank in 2 minutes and 15 minutes respectively. Both the pipes are opened together but 4 minutes after the start the pipe A is turned off. How much time will it take to fill the tank?

A.

9 min

B.

10 min

C.

11 min

D.

12 min

Answer with explanation

Answer: Option BExplanation

4/12 + x/15 = 1

x = 10

Workspace

A tank is filled in 10 hours by three pipes A, B and C. Pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?

A.

70 hours

B.

30 hours

C.

35 hours

D.

50 hours

Answer with explanation

Answer: Option AExplanation

Workspace

A large tanker can be filled by two pipes A and B in 60 minutes 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.

15 min

B.

20 min

C.

27.5 min

D.

30 min

Answer with explanation

Answer: Option DExplanation

Workspace

Bucket P has thrice the capacity as bucket Q. It takes 80 turns for bucket P to fill the empty drum. How many turns it will take for both the buckets P and Q, having each turn together to fill the empty drum?

A.

30

B.

45

C.

60

D.

80

Answer with explanation

Answer: Option CExplanation

Workspace

A.

30 hours

B.

15 hours

C.

10 hours

D.

6 hours

Answer with explanation

Answer: Option BExplanation

Let the first pipe alone can fill the tank in x hours

Then the second pipe can fill the tank in (x-5) hours

and the third pipe can fill the tank in (x-5)-4 = (x-9) hours

part filled by first pipe and second pipe together in 1 hr = part filled by third pipe in 1 hr

Workspace

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