Question

a cistern can be filled by a tap in 7 hours and emptied by an outlet pipe in 9 hours. how many will it take to fill the cistern if both the tap and the pipe are opened together..​

Answer 1

Answer:

Let x hours be required to fill

7 hours to fill tap

so volume filled in 1 hour =1/7th of total volume

similarly pipe in 1 hour empties =1/9 th of total volume

therefore net filling of cistern in one hour=1/7 - 1/9=2/63

Therefore (2/63)×x=1( whole volume)

x=63/2 hours

Answer 2

Answer:

SEE THE ATTACHMENT

Step-by-step explanation:

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