A boat runs 16 km downstream in 2 hours and the same distance upstream in 4 hours. What is the speed of the boat in still water?

Given data

• Downstream speed d = 16/2 = 8 km/h
• Upstream speed u = 16/4 = 4 km/h

Concept / Approach

• Still-water speed v = (u + d)/2.

Step-by-step calculationv = (8 + 4)/2 = 6 km/h

Final Answer6 km/h