In 1 hour, a boat goes 9 km along the stream and 3 km against the stream. The speed of the boat in still water (in km/hr) is : Answers:	A) 3 km/hr.	B) 2 km/hr.	C) 6 km/hr.	D) 8 km/hr.	E) 5 km/hr.
Speed in still water = 1/2(9 + 3) km/hr   = 6 km/hr. ANSWER :6 km/hr.
<result>C</result>
In 1 hour, a boat goes 9 km along the stream and 3 km against the stream. The speed of the boat in still water (in km/hr) is :