In a stream running at $2 \, km/h$,a motorboat goes $10 \, km$ upstream and returns to the starting point in $55 \, min$. Find the speed of the motorboat in still water (in $km/h$).

$A$ man can row $44 \text{ km}$ downstream in $4 \text{ hours}$. If the man's rowing rate in still water is $8 \text{ km/hr}$,then find in what time will he cover $25 \text{ km}$ upstream? (in $\text{hours}$)

$A$ man can row at $10 \text{ km/h}$ in still water. If he takes a total of $5 \text{ h}$ to go to a place $24 \text{ km}$ away and return,then the speed of the water current is $... \text{ km/h}$.

$A$ boat covers a certain distance downstream in $2$ $hours$,but takes $4$ $hours$ to return upstream to the starting point. If the speed of the stream is $3$ $km/h$,find the speed of the boat in still water (in $km/h$).

$A$ boatman takes twice as long to row a distance against the stream as to row the same distance with the stream. Find the ratio of the speed of the boat in still water to the speed of the stream.

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 $hrs$).