$A, B, C$ are pipes attached to a cistern. $A$ and $B$ can fill it in $20$ and $30$ minutes respectively,while $C$ can empty it in $15$ minutes. If $A, B, C$ are kept open successively for $1$ minute each,how soon will the cistern be filled? (in minutes)

Taps $A, B$ and $C$ are attached to a tank. The rates of water flow through them are $42 \ L/h$,$56 \ L/h$,and $48 \ L/h$ respectively. $A$ and $B$ are inlet taps,while $C$ is an outlet tap. If all the taps are opened simultaneously,the tank is filled in $16 \ h$. What is the capacity of the tank (in $L$)?

If pipe $P$ can fill a tank in $p$ hours and pipe $Q$ can empty the same tank in $q$ hours (where $q > p$),and both pipes are opened simultaneously,in how many hours $(r)$ will the tank be filled?

Two pipes can separately fill a tank in $20$ $hrs$ and $30$ $hrs$ respectively. Both the pipes are opened to fill the tank,but when the tank is $\frac{1}{3}$ full,a leak develops in the tank through which $\frac{1}{3}$ of the water supplied by both the pipes per hour leaks out. What is the total time (in $hrs$) taken to fill the tank?

$A$ cistern has two taps which fill it in $12$ $minutes$ and $15$ $minutes$ respectively. There is also a waste pipe in the cistern. When all the pipes are opened,the empty cistern is filled in $20$ $minutes$. How long will the waste pipe take to empty a full cistern?

$A$ tank can be filled by pipe $A$ in $2$ $hours$ and pipe $B$ in $6$ $hours.$ At $10 \, am$ pipe $A$ was opened. At what time will the tank be filled if pipe $B$ is opened at $11 \, am$?