Two pipes $A$ and $B$ can fill a tank in $24$ $min.$ and $48$ $min.$ respectively. If both the pipes are opened simultaneously,after how much time (in $minutes$) $B$ should be closed so that the tank is full in $20$ $minutes$?

$10$ buckets of water fill a tank when the capacity of each bucket is $12$ litres. How many buckets will be needed to fill the same tank,if the capacity of each bucket is $8$ litres?

An outlet pipe can empty a cistern in $3$ $h$. In what time (in $h$) will the pipe empty two-third part of the cistern?

There are two taps $A$ and $B$ to fill up a water tank. The tank can be filled in $40$ $min,$ if both taps are on. The same tank can be filled in $60$ $min,$ if tap $A$ alone is on. How much time (in $minutes$) will tap $B$ alone take to fill up the same tank?

One fill pipe $A$ is $3$ times faster than second fill pipe $B$ and takes $32$ minutes less than the fill pipe $B$. When will the cistern be full if both the pipes are opened together?

$A$ pump can fill a tank with water in $2$ $hours$. Because of a leak,it took $2 \frac{1}{3}$ $hours$ to fill the tank. The leak can drain all the water of the tank in (in $hours$)?