In one hour, a boat goes 11 km along the stream and 3 km against the stream. the sped of the boat in still water (in km/hr) is :  Choose the correct choice from the following answers:
A) 3	B) 5	C) 7	D) 9	E) 10

Rationale: "solution speed in still water = 1 / 2 ( 11 + 3 ) km / hr = 7 kmph . answer c"
Answer: C