In one hour, a boat goes 11 km along the stream and 5 km against the stream. The speed of the boat in still water in ( km/hr) is  Choose the correct choice from the following answers:
A) 3
B) 5
C) 8
D) 9
E) 7

Rationale: "solution speed in still water = 1 / 2 ( 11 + 5 ) km / hr = 8 km / hr . answer c"
Answer: C