$A$ boat can travel with a speed of $13 \text{ km/hr}$ in still water. If the speed of the stream is $4 \text{ km/hr}$,the time taken by the boat to travel $63 \text{ km}$ in the opposite direction (upstream) is........$hrs$.

$A$ man can row $7 \frac{1}{2} \, km/hr$ in still water. If in a river running at $1.5 \, km/hr$,it takes him $50 \, minutes$ to row to a place and back,how far off is the place? (in $km$)

The speed of a boat in still water is $10\, km/h$. It covers an upstream distance of $45\, km$ in $6\, h$. The speed (in $km/h$) of the stream is:

$A$ boat takes $3$ $hours$ to travel from place $M$ to $N$ downstream and back from $N$ to $M$ upstream. If the speed of the boat in still water is $4$ $km/h$,what is the distance between the two places? (in $km$)

$A, B$ 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?

$A$ man can row upstream $36 \text{ km}$ in $6 \text{ hours}$. If the speed of a man in still water is $8 \text{ km/hr}$,find how much distance he can cover downstream in $10 \text{ hours}$? (in $\text{km}$)