Two pipes $A$ and $B$ can fill a tank in $1$ $h$ and $75$ $min,$ respectively. There is also an outlet $C$. If all the three pipes are opened together, the tank is full in $50$ $min.$ How much time (in $minutes$) will be taken by $C$ to empty the full tank?

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 $min$)?

Two pipes $A$ and $B$ can fill a tank in $37 \frac{1}{2}$ minutes and $45$ minutes respectively. If both pipes are opened together,after how much time (in minutes) should pipe $B$ be closed so that the tank is full in exactly $30$ minutes?

Pipes $A$ and $B$ can fill a tank in $5$ $hours$ and $6$ $hours$ respectively. Pipe $C$ can empty it in $12$ $hours.$ If all the three pipes are opened together,then the tank will be filled in

Two taps $A$ and $B$ can fill a tank in $20 \text{ min}$ and $30 \text{ min}$,respectively. An outlet pipe $C$ can empty the full tank in $15 \text{ min}$. If $A, B$,and $C$ are opened alternatively,each for $1 \text{ min}$,how long (in $\text{min}$) will the tank take to be filled?

$A$ cistern has two pipes. One can fill it in $8 \, h$ and the other can empty it in $5 \, h$. In how many $hours$ will the cistern be emptied if both the pipes are opened together when $\frac{3}{4}$ of the cistern is already full of water?