A boat moves downstream at the rate of 1 km in $$7{1\over 2}$$ minutes and upstream at the rate of 5 km an hour. What is the speed of the boat in the still water?  

A man rows 12 km in 5 hours against the stream and the speed of current being 4 kmph, What time will be taken by him to row 15 km with the stream? 

The water in a river is flowing at a rate of 4 km/hr. If the width and depth of the river are 8m and 4m respectively, then how much water will enter the sea in 15 minutes? 

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

A motorboat, whose speed is 45 km./hr. in still water goes 180 km. downstream and comes back in a total of 9 hours. The speed of the stream (in km/hr.) is-

A man swims downstream distance of 15 km in 1 hour. If the speed of the current is 5 km/ hr, the time taken by the man to swim the same distance upstream is : 

A man can row 30 km downstream and return in a total of 8 hours. If the speed of the boat in still water is four times the speed of the current, then the speed of the current is: 

The speed of the current is 5 km / hour. A motorboat goes 10 km upstream and back again to the starting point in 50 minutes. The speed (in km / hour) of the motorboat in still water is: