A man can row with the stream at 7 km/h and against the stream at 3 km/h. His speed in still water is

A 6.5 km/h

B 7 km/h

C 5 km/h

D 6 km/h

E None of these

Correct Answer: Option C

Given, man can row along with stream at speed of = 7 km/hr

And man can row against the stream at speed of = 3 km/hr

∵ Speed in still water = (upward speed + downward speed)/2

∴ Speed in still water = (7 + 3)/2

Speed in still water = 5 km/hr