In a stream running at $2 \, km/hr$,a water scooter goes $10 \, km$ upstream and back again to the starting point in $55 \, minutes$. Find the speed of the water scooter in still water (in $km/hr$).

$A$ boatman rows $1\, km$ in $5\, min$ along the stream and $6\, km$ in $1\, h$ against the stream. The speed of the stream is in $km/h$:

$A$ boatman can row $48\, km$ downstream in $4\, hours$. If the speed of the current is $5\, km/h$,then find in what time will he be able to cover $8\, km$ upstream? (in $hours$)

The speed of a boat in still water is $4 \, km/h$ and the speed of the current is $2 \, km/h$. If the time taken to reach a certain distance upstream is $9 \, hours$,find the time it will take to go the same distance downstream (in $hrs$).

In a stream running at $2 \ km/h$,a motorboat goes $6 \ km$ upstream and back again to the starting point in $33 \ minutes$. Find the speed of the motorboat in still water. (in $km/h$)

$A$ boat goes $48\, km$ downstream in $20\, h$. It takes $4\, h$ more to cover the same distance against the stream. What is the speed of the boat in still water? (in $km/h$)