The speed of a boat along the stream is $12 \, km/h$ and against the stream is $8 \, km/h$. The time taken by the boat to sail $24 \, km$ in still water is:

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?

$P, Q, R$ are three towns on a river which flows uniformly. $Q$ is equidistant from $P$ and $R$. $A$ man rows from $P$ to $Q$ and returns in $10 \, h$. He can row from $P$ to $R$ in $4 \, h$. The ratio of the speed of the man in still water to the speed of the current is

If a man's rate with the current is $12\, km/h$ and the rate of current is $1.5\, km/h$,then the man's rate against the current in $km/h$ is...........

$A$ 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.......$km/hr$

$A$ 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 $\text{km/h}$).