A crew team rows a boat at a rate of 20 km/h in still water . In practice on a river , the team rows for 30 minutes up the river , and then for 30 minutes down the river . The speed of the river current is 1.5 km/h . How long did it take for them to return to the starting point ?
A crew team rows a boat at a rate of 20 km/h in still water . In practice on a river , the team rows for 30 minutes up the river and then for 30 minutes down the river . The speed of the river current is 1.5 km/h . How much farther did they travel in the 2nd 30 minutes ?