Pipe $A$ can fill a cistern in $6 \, h$ and pipe $B$ can fill it in $8 \, h$. Both the pipes are opened simultaneously,but after $2 \, h$ pipe $A$ is closed. How many hours will $B$ take to fill the remaining part of the cistern?

Two pipes can fill a cistern separately in $24$ $minutes$ and $40$ $minutes$ respectively. $A$ waste pipe can drain off $30 \text{ litres per minute}$. If all the three pipes are opened,the cistern fills in one $hour$. The capacity (in $litres$) of the cistern is:

If three taps are opened together,a tank is filled in $12$ $hrs$. One of the taps can fill it in $10$ $hrs$ and another in $15$ $hrs$. How many $hours$ does the third tap take alone to empty it completely?

$A$ tank can be filled by one tap in $20$ $min$ and by another tap in $60$ $min$. Both the taps are kept open for $5$ $min$ and then the $1$st tap is shut off. After this,how much more time (in $min$) will it take for the tank to be completely filled?

$A$ cistern has three pipes $A, B$ and $C$. Pipes $A$ and $B$ can fill it in $3 \, h$ and $4 \, h$, respectively, while pipe $C$ can empty the completely filled cistern in $1 \, h$. If pipes are opened in order at $3:00 \, pm$, $4:00 \, pm$ and $5:00 \, pm$, respectively, at what time will the cistern be empty?

Three taps $A, B$ and $C$ fill a tank in $20$ min,$15$ min and $12$ min,respectively. If all the taps are opened simultaneously,how long will they take to fill $40 \%$ of the tank (in $min$)?