Inlet $A$ is four times faster than inlet $B$ to fill a tank. If inlet $A$ alone can fill it in $15$ minutes,how long will it take if both the pipes are opened together? (in minutes)

If a pipe fills a tank in $6 \ h$,then what part of the tank will the pipe fill in $1 \ h$?

Two pipes $A$ and $B$ can fill a tank in $24$ $minutes$ and $32$ $minutes$ respectively. If both the pipes are opened simultaneously,after how much time (in $minutes$) should $B$ be closed so that the tank is full in $18$ $minutes$?

Two taps $A$ and $B$ can fill a tank in $10$ $hours$ and $15$ $hours$,respectively. If both the taps are opened together,the tank will be full in (in $hours$):

Two inlet pipes can fill a cistern in $10$ $hours$ and $12$ $hours$ respectively,and an outlet pipe can empty $80$ $gallons$ of water per hour. All three pipes working together can fill the empty cistern in $20$ $hours$. What is the capacity (in $gallons$) of the 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?