Speed of a boat in standing water is $9 \text{ km/h}$ and the speed of the stream is $1.5 \text{ km/h}$. $A$ man rows to a place at a distance of $105 \text{ km}$ and comes back to the starting point. The total time taken by him is (in $\text{ hours}$)

$A$ river is flowing at a speed of $5\, km/h$ in a particular direction. $A$ man,who can swim at a speed of $20\, km/h$ in still water,starts swimming along the direction of flow of the river from point $A$ and reaches another point $B$ which is at a distance of $30\, km$ from the starting point $A$. On reaching point $B$,the man turns back and starts swimming against the direction of flow of the river and stops after reaching point $A$. The total time taken by the man to complete his journey is:

$A$ man can swim at the rate of $4\, km/h$ in still water. If the speed of the water is $2\, km/h$,then the time taken by him to swim $10\, km$ upstream is.........$h$.

The ratio of the speed of a motorboat to the speed of the water current is $36: 5$. The boat travels along with the current in $5\, h\, 10\, min$. How long will it take to return?

$A$ boat goes $14 \ km$ upstream in $42 \ minutes$. The speed of the stream is $4 \ km$. The speed of the boat in still water is .......... $km/h$.

$A$ man can row at a speed of $4.5 \text{ km/hr}$ in still water to a certain upstream point and back to the starting point in a river which flows at $1.5 \text{ km/hr}$. Find his average speed for the total journey in $\text{km/hr}$.