A pipe can fill a tank in x hours and another can empty it in y hours. They can

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Question
A pipe can fill a tank in x hours and another can empty it in y hours. They can together fill it in (y > x)?
Options
A. (x - y) hours
B. (y - x ) hours
C. xy / (x - y) hours
D. xy / ( y - x) hours

Correct Answer

xy / ( y - x) hours

Explanation

Net filling in 1 hour = (1/x - 1/y) = (y - x) / xy
? Time taken to fill the tank = xy / (y - x) hrs.

Pipes and Cistern problems

Search Results

1.
One tap can fill a cistern in 2 hours and another can empty the cistern in 3 hours. How long will they take to fill the cistern if both the taps are opened?
Options
A. 5 hours
B. 6 hours
C. 7 hours
D. 8 hours

2.
A cistern can be filled by two pipes A and B in 4 hours and 6 hours respectively. When full, the tank can be emptied by a third pipe C in 8 hours . If all the taps be turned on at the same time, the cistern will be full in?
Options
A. 3 hours 18 min.
B. 3 hours 26 min.
C. 3 hours 42 min.
D. 3 hours 48 min.

3.
A tap can fill a tank in 16 minutes and another can empty it in 8 minutes. If the tank is already half full and both the taps are opened together, the tank will be?
Options
A. Filled in 12 min.
B. Emptied in 12 min.
C. Filled in 8 min.
D. Emptied in 8 min.

4.
Three pipes A, B and C can fill a tank separately in 8 h,10 h and 20h, respectively. Find the time taken by all the three pipes to fill the tank when these pipes are opened together?
Options
A. 57/11 h
B. 47/11 h
C. 87/11 h
D. 37/11 h

5.
An outlet pipe can empty a cistern in 30 min, then what part of the cistern will it empty in 1 min?
Options
A. 1/20
B. 1/15
C. 1/30
D. 1/18

6.
A tap can fill a cistern in 8 hours and another can empty it in 16 hours. If both the taps are opened simultaneously, the time (in hours) to fill the tank is?
Options
A. 8
B. 10
C. 16
D. 24

7.
Pipes A and B can fill a tank in 10 hours and 15 hours respectively. Both together can fill it in?
Options
A. 121/2 hours
B. 6 hours
C. 5 hours
D. None of these

8.
Three are two taps to fill a tank while a third to empty it. When the third tap is closed, they can fill the tank in 10 minutes and 12 minutes respectively. If all the three taps be opened, the tank is filled in 15 minutes. If the first two taps are closed, in what time can the third tap empty the tank when it is full?
Options
A. 7 min.
B. 9 min. and 32 sec.
C. 8 min. and 34 sec.
D. 6 min.

9.
A tap can fill a tank in 25 minutes and another can empty it in 50 minutes. Find whether the tank will be filled up or emptied and in how many minutes?
Options
A. Tank is emptied in 20 minutes
B. Tank is filled up in 50 minutes
C. Tank is filled up in 20 minutes
D. Tank is emptied in 25 minutes

10.
Two pipes A and B can fill a tank in 18 and 6 h, respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?
Options
A. 41/2h
B. 7 h
C. 6 h
D. 10 h

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