$A$ man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is:

$A$ man takes $3$ $hours$ $45$ $minutes$ to row a boat $15 \; km$ downstream of a river and $2$ $hours$ $30$ $minutes$ to cover a distance of $5 \; km$ upstream. Find the speed of the river current in $km/hr$.

Aditya can row with the stream at $10 \text{ km/h}$ and against the stream at $6 \text{ km/h}$. His speed in still water is .......... $\text{km/h}$.

In one hour,a boat goes $11 \ km$ along the stream and $5 \ km$ against the stream. The speed of the boat in still water (in $km/hr$) is

$A$ man can row at a speed of $10 \text{ km/h}$ in still water to a certain upstream point and back to the starting point in a river which flows at $4 \text{ km/h}$. Find his average speed for the total journey (in $\text{km/h}$).

$A$ man can row $15\, km$ downstream in $3\, hours$ and $5\, km$ upstream in $2.5\, hours$. His speed in still water in $(km/hr)$ is: