$A$ person can row with the stream at $8 \text{ km/h}$ and against the stream at $4 \text{ km/h}$. The speed of the current is (in $\text{km/h}$):

If a boat goes upstream at a speed of $21\, km/h$ and comes back the same distance at $28\, km/h$,what is the average speed (in $km/h$) for the total journey?

$A$ man's speed with the current is $15 \, km/hr$,and the speed of the current is $2.5 \, km/hr$. The man's speed against the current is.......$km/hr$

The speed of a boat in still water is $10\, km/hr$. If it can travel $26\, km$ downstream and $14\, km$ upstream in the same time,the speed of the stream is.....$km/hr$.

$A$ boat travels $2\, km$ upstream in a stream flowing at $3\, km/h$ and then returns downstream to the starting point in $30\, minutes$. The speed of the boat in still water is........$km/h$.

$A$ man can swim $3 \text{ km/h}$ in still water. If the velocity of the stream is $2 \text{ km/h}$,the time taken by him to swim to a place $10 \text{ km}$ upstream and back is (in hours):