A rower whose speed is 9 km/hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 3 km/hr. What is the rower's average speed (in km/hr) for the total journey?	Choose the correct choice from the following options:
A) 7 B) 8 C) 9 D) 10 E) 11
time upstream = d / 6   time downstream = d / 12   total time = d/6 + d/12 = d/4   average speed = 2d / (d/4) = 8 km/hr   The answer is 8.
<result>B</result>
A rower whose speed is 9 km/hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 3 km/hr. What is the rower's average speed (in km/hr) for the total journey?