In one hour, a boat goes 8 km/hr along the stream and 2 km/hr against the stream. The speed of the boat in still water (in km/hr) is:
Choose the correct option
A) 3 km/hr  B) 4 km/hr  C) 5 km/hr  D) 6 km/hr  E) 8 km/hr
Upstream relative speed is u + v=8km/hr   Downstream speed is u-v = 2   Where u = speed of boat in still water and v is speed of stream   Then adding two equations u+v + u-v =8+2   2u=10   Finally, u=5.   ANSWER : 5 km/hr
<result>C</result>
In one hour, a boat goes 8 km/hr along the stream and 2 km/hr against the stream. The speed of the boat in still water (in km/hr) is: