A man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 0.5 kmph, find his average speed for the total journey?  Choose the correct answer:
A) 4
B) 3.5
C) 3
D) 3.1
E) 2.8
M = 4.5   S = 2.5   3.1S = 7   US = 2   AS = (2 * 7 * 2) /9 = 3.1   Answer: 3.1
<result>D</result>
A man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 0.5 kmph, find his average speed for the total journey?