$A$ man can row at $5 \, km/h$ in still water. If the velocity of the current is $1 \, km/h$ and it takes him $1 \, h$ to row to a place and come back,how far is the place? (in $km$)

$A$ boat travels $18 \, km$ upstream in $6 \, hours$. How long (in $hours$) will it take to cover the same distance downstream if the speed of the current is one-fourth the speed of the boat in still water?

$A$ man can row $7 \frac{1}{2} \, km/hr$ in still water. If in a river running at $1.5 \, km/hr$,it takes him $50 \, minutes$ to row to a place and back,how far off is the place? (in $km$)

$A$ boat running downstream covers a distance of $16\, km$ in $2\, hours,$ while for covering the same distance upstream,it takes $4\, hours.$ What is the speed of the boat in still water? (in $km/hr$)

The ratio of the speed of a motorboat to that of the water current is $36 : 5$. The motorboat travels along with the current in $5 \, h \, 10 \, min$. Find the time taken by the motorboat to return.

$A$ man swimming in a stream which flows at $1.5 \, km/hr$ finds that in a given time he can swim twice as far with the stream as he can against it. At what rate does he swim in still water? (in $km/hr$)