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:

$P, Q, R$ 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

$A$ boat goes $48\, km$ downstream in $20\, h$. It takes $4\, h$ more to cover the same distance against the stream. What is the speed of the boat in still water? (in $km/h$)

$A$ man can row against the current $\frac{3}{4}$ of a kilometre in $15$ minutes and returns the same distance in $10$ minutes. The ratio of his speed to that of the current is

$P$,$Q$,and $R$ are three towns on a river that flows uniformly. $Q$ is equidistant from $P$ and $R$. $I$ row from $P$ to $Q$ and back in $10$ $hours$,and $I$ can row downstream from $P$ to $R$ in $4$ $hours$. Compare the speed of my boat in still water with that of the river.

$A$ man rows upstream $12 \text{ km}$ and downstream $28 \text{ km}$,taking $5 \text{ hours}$ each time. The velocity of the water current is ......... $\text{km/h}$.