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 boat goes 30 km upstream and 44 km downstream in 10 hours. In 13 hours, it can go 40 km upstream and 55 km downstream. The speed of the boat in still water is. 

A motorboat can travel at 10 km/hr. in still water it travelled 91 km downstream in a river and then returned taking at together 20 hours. Find the rate of flow of the river 

A boat takes half time in moving a certain distance downstream than upstream. what is the ratio between the rate in still water and the rate of current? 

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-