A man whose speed is 6.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 2.5 kmph, find his average speed for the total journey ?  Select:
A) 1 kmph
B) 5 kmph
C) 5.5 kmph
D) 4 kmph
E) 7 kmph

Rationale: "explanation : speed of man = 6.5 kmph speed of stream = 2.5 kmph speed in downstream = 9 kmph speed in upstream = 4 kmph average speed = ( 2 x 9 x 4 ) / 13 = 5.5 kmph . answer : c"
Answer: C