In one hour,a boat goes 13 km along the stream and 9 km against the stream.The speed of the boat in still water (in km/hr) is :	Answers:
A) 3
B) 5
C) 11
D) 9
E) 10

Rationale: "solution speed in still water = 1 / 2 ( 13 + 9 ) kmph . = 11 kmph . answer c"
Answer: C