A boat running downstreams covers a distance of 30 kms in 2 hours. While coming back the boat takes 6 hours to cover the same distance. If the speed  of the current is half that of the boat, what is the speed of that boat in kmph?

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? 

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. 

In a river the distance between two points is 80 km. A boat which rows 13 km/h in still water goes downstream from the first point to the second and returns upstream to starting point in 13 hrs., then find the speed of current. 

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? 

Speed of a boat in still water is 6 km/hr and speed of the current is 2 km/hr. If boat takes four hours more in upstream than in the downstream to cover ‘D’ km, then find time take by boat to cover ‘D’ km in still water?

If a boat goes upstream at a speed of 24 km/hr and comes back the same distance at 40 km/hr. What is the average speed (in km/hr) for the total journey?

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: