A Cistern Can Be Filled By A Tap In 4 Hours While It Can Be Emptied B

1.	A Cistern Can Be Filled By A Tap In 4 Hours While It Can Be Emptied By Another Tap In 9 Hours. If Both Taps Are Opened Simultaneously, Then After How Much Time Will The Cistern Get Filled ?
Answer» Time taken by tap A to fill the cistern=4 HRS so WORK done by tap A in 1 hour = 1/4th Time taken by tap B to EMPTY the FULL cistern = 9 hours so work done by tap B in 1 hour = 1/9th => Work done by (A + B) in 1 hour=(1/4 - 1/9)=5/36 Therefore, the tank will fill the cistern = 36/5 hours=7.2 hours. Time taken by tap A to fill the cistern=4 hrs so work done by tap A in 1 hour = 1/4th Time taken by tap B to empty the full cistern = 9 hours so work done by tap B in 1 hour = 1/9th => Work done by (A + B) in 1 hour=(1/4 - 1/9)=5/36 Therefore, the tank will fill the cistern = 36/5 hours=7.2 hours.

A Cistern Can Be Filled By A Tap In 4 Hours While It Can Be Emptied By Another Tap In 9 Hours. If Both Taps Are Opened Simultaneously, Then After How Much Time Will The Cistern Get Filled ?

Answer»

Time taken by tap A to fill the cistern=4 HRS

so WORK done by tap A in 1 hour = 1/4th

Time taken by tap B to EMPTY the FULL cistern = 9 hours

so work done by tap B in 1 hour = 1/9th

=> Work done by (A + B) in 1 hour=(1/4 - 1/9)=5/36

Therefore, the tank will fill the cistern = 36/5 hours=7.2 hours.

Time taken by tap A to fill the cistern=4 hrs

so work done by tap A in 1 hour = 1/4th

Time taken by tap B to empty the full cistern = 9 hours

so work done by tap B in 1 hour = 1/9th

=> Work done by (A + B) in 1 hour=(1/4 - 1/9)=5/36

Therefore, the tank will fill the cistern = 36/5 hours=7.2 hours.