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 $km/hr$).

$A$ man can row $9 \text{ km/hr}$ in still water. If the river is running at $3 \text{ km/hr}$,it takes $3 \text{ hours}$ more to row upstream than to row downstream for the same distance. How far is the place? (in $\text{km}$)

Speeds of a boat along the current and against the current are $10 \ km/hr$ and $8 \ km/hr$ respectively. What is the speed (in $km/hr$) of the current?

$A, B$ and $C$ are situated on the bank of a river which is flowing at a constant rate. $B$ is at an equal distance from $A$ and $C$. $A$ swimmer Avinash takes $10 \, h$ to swim from $A$ to $B$ and $B$ to $A$. Also,he takes $8 \, h$ to swim from $A$ to $C$ in downstream. What is the ratio of the speed of Avinash in still water to the speed of the stream?

$A$ boat can travel with a speed of $13\, km/hr$ in still water. If the speed of the stream is $4\, km/hr,$ find the time taken by the boat to go $68\, km$ downstream. (in $hours$)

$A$ boat travels upstream from $B$ to $A$ and downstream from $A$ to $B$ in $3$ $hours$. If the speed of the boat in still water is $9\, km/h$ and the speed of the current is $3\, km/h$,the distance between $A$ and $B$ is........$km$.