A boat goes downstream at 18 km/h and upstream at 12 km/h. What is the speed of the boat in still water?
Correct answer: A. 15 km/h
Speed in still water = (downstream + upstream) ÷ 2 = (18 + 12) ÷ 2 = 15 km/h. The stream's speed is (18 − 12) ÷ 2 = 3 km/h.
hard