A man can row at 5 km/h in still water. The current is 1 km/h. If a to-and-fro trip takes 1 hour, how far is the place?

Given data

• Still-water speed = 5 km/h; current = 1 km/h
• Downstream speed = 5 + 1 = 6 km/h
• Upstream speed = 5 − 1 = 4 km/h
• Total time (down + up) = 1 h

Concept / Approach

• Let one-way distance be d. Then d/6 + d/4 = 1.

Step-by-step calculation
d \/ 6 + d \/ 4 = 1 ⇒ d(1/6 + 1/4) = 1d(5/12) = 1 ⇒ d = 12/5 = 2.4 km

Final Answer
2.4 km