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 is :
Choose the correct option.
A) 3
B) 5
C) 8
D) 9
E) 10

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