192
Q:

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:   D) 14 min. 40 sec.



Explanation:

Part filled in 4 minutes =4(1/15+1/20) = 7/15

 

Remaining part =(1-7/15) = 8/15

 

Part filled by B in 1 minute =1/20 : 8/15 :: 1:x 

x = (8/15*1*20) = 1023min = 10min 40sec

The tank will be full in (4 min. + 10 min. + 40 sec.) = 14 min. 40 sec

Q:

Pipes A and B can fill a tank in 10 hours and 40 hours, respectively. C is an outlet pipe attached to the tank. If all the three pipes are opened simultaneously, it takes 80 minutes more time than what A and B together take to fill the tank. A and B are kept opened for 7 hours and then closed and C was opened. C will now empty the tank in:

 

A) 49 hours B) 38.5 hours
C) 42 hours D) 45.5 hours
 
Answer & Explanation Answer: A) 49 hours

Explanation:
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1 233
Q:

Pipe A can fill an empty cistern in 15 hours while Pipe B takes 25 hours to fill it. Initially Pipe A is left open for some time and then closed and Pipe B is switched on immediately. In all the cistern rakes 21 hours to be filth How long was Pipe A open?

 

A) 3 hours B) 7.5 hours
C) 6 hours D) 9 hours
 
Answer & Explanation Answer: C) 6 hours

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0 449
Q:

Pipes A, B and C together can fill a tank in 4 hours. Pipes A and B together can fill the tank in 9 hours. If pipes A, B and C are opened simultaneously, and after 3 hours, pipes A and B are closed, then how many hours will C alone require to fill the tank?

 

A) 2.25 B) 2
C) 1.5 D) 1.8
 
Answer & Explanation Answer: D) 1.8

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1 323
Q:

Pipes A and C can fill an empty cistern in 7 and 10.5 hours, respectively while Pipe B can drain the filled cistern in 5.25 hours. If the three pipes are turned on together when the cistern is empty, how many hours will it take for the cistern to be23full?

 

A) 121 B) 12
C) 14 D) 15.75
 
Answer & Explanation Answer: C) 14

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2 285
Q:

Pipes A, B and C are attached to an empty cistern. While the first two can fill the cistern in 6.6 and 16.5 hours respectively, the third can drain the cistern, when filled, in 9.9 hours. If all the three pipes are opened simultaneously when the cistern is three-fifths full, how many hours will be needed to fill the cistern?

 

 

A) 3.5 B) 4
C) 3.6 D) 3.75
 
Answer & Explanation Answer: C) 3.6

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0 309
Q:

Two pipes A and B can fill an empty cistern in 1.8 and 2.7 hours, respectively. Pipe C can drain the entire cistern in 4.5 hours when no other pipe is in operation. Initially when the cistern was empty Pipe A and  Pipe C were turned on. After a few hours Pipe A was turned off and Pipe B was turned on instantly. In all it took 5.5 hours to fill the cistern. For how many hours was Pipe B turned on?

 

A) 5 B) 4.5
C) 3 D)
 
Answer & Explanation Answer: B) 4.5

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0 370
Q:

Pipe A could fill an empty cistern in 18 hrs while pipe B can drain a filled cistern in 30 hrs. When the cistern is empty, pipe A is turned on for an hour and then turned off. The pipes were alternately left open for an hour each time till the cistern was full. How much time did it take for the cistern to be full?

A) 90 hrs B) 86 hrs 40 min
C) 45 hrs D) 86 hrs 48 min
 
Answer & Explanation Answer: D) 86 hrs 48 min

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0 348
Q:

Pipe A can fill an empty cistern in 6 hours while along with Pipe B it can fill it up in 4 hours. Only Pipe B is on for an hour after which Pipe A is also turned on. How much time will it take in all to fill up the cistern?

A) 4 hrs 25 min B) 4 hrs 15 min
C) 4 hrs 40 min D) 4 hrs
 
Answer & Explanation Answer: D) 4 hrs

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1 547