$A$ tank is filled in $5$ $hours$ by three pipes $A, B$ and $C$. The pipe $C$ is twice as fast as $B$ and $B$ is twice as fast as $A$. How much time (in $hours$) will pipe $A$ alone take to fill the tank?

$A$ water tank is $\frac{2}{5}$ full. Pipe $A$ can fill the tank in $10$ $minutes$ and pipe $B$ can empty it in $6$ $minutes$. If both the pipes are open,then how long will it take to empty or fill the tank completely?

$A$ tap can fill a cistern in $40$ $min$ and a second tap can empty the filled cistern in $60$ $min$. By mistake, without closing the second tap, the first tap was opened. In how many $minutes$ will the empty cistern be filled?

$A$ pipe can empty a tank in $15$ $hrs$ and another pipe can empty it in $10$ $hrs$. If both the pipes are opened simultaneously, find the time in $hrs$ in which a full tank is emptied?

$A$ cistern has a leak which would empty it in $8$ $hours$. $A$ tap is turned on which admits $6$ $litres$ a minute into the cistern,and it is now emptied in $12$ $hours$. How many $litres$ does the cistern hold?

$A$ pipe can fill a tank with water in $3 \, h$. Due to a leak at the bottom,it takes $3 \frac{1}{2} \, h$ to fill it. In what time (in $hours$) will the leak empty the fully filled tank?