$A$ tap can fill a tank in $6$ $h$. After half the tank is filled,three more similar taps are opened. What is the total time taken to fill the tank completely?

There are two inlets $A$ and $B$ connected to a tank. $A$ and $B$ can fill the tank in $16 \text{ h}$ and $10 \text{ h}$,respectively. If both the pipes are opened alternately for $1 \text{ h}$,starting with $A$,then how much time will the tank take to be filled?

Two taps $A$ and $B$ can fill a water tank in $20$ $min$ and $24$ $min$ respectively,and a third tap $C$ empties the tank at a rate of $3$ $gallons$ per $min$. If all three taps $A$,$B$,and $C$ are opened together,the tank is filled in $15$ $min$. What is the capacity of the tank in $gallons$?

An empty tank can be filled by pipe $A$ in $4$ $h$ and by pipe $B$ in $6$ $h$. If the two pipes are opened for $1$ $h$ each alternately,starting with pipe $A$,then in how much time will the tank be filled?

$18$ pumps can fill a reservoir of capacity $1440 \text{ kilo liter}$ in $5 \text{ hours}$. How many $\text{hours}$ are required to fill a reservoir of capacity $1920 \text{ kilo liter}$ by $8$ pumps?

Pipe $A$ can fill an empty tank in $6$ $hours$ and pipe $B$ in $8$ $hours$. If both the pipes are opened and after $2$ $hours$ pipe $A$ is closed,how much time will pipe $B$ take to fill the remaining tank?