SOLUTION: Hi Luke can canoe at a speed of 3km per hour on a still lake. Luke took a canoe down a river at 2km per hour. He then returned upstream to his starting point. What was his aver

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Question 1184982: Hi
Luke can canoe at a speed of 3km per hour on a still lake. Luke took a canoe down a river at 2km per hour.
He then returned upstream to his starting point.
What was his average speed for the trip.
Thanks
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52747) About Me  (Show Source):
You can put this solution on YOUR website!
.
Luke can canoe at a speed of 3km per hour on a still lake. Luke took a canoe down a river at 2km per hour.
He then returned upstream to his starting point.
What was his average speed for the trip.
Thanks
~~~~~~~~~~~~~~~~~ 


Under given conditions, the effective rate canoeing downstream is  3 + 2 = 5 km/h,

while the effective rate canoeing upstream is  (3-2) = 1 km/h.



So, in this problem, you have a body moving with the rate of  u = 5 km/h  in one direction (downstream)

and moving with the rate of  v = 1 km/h in the opposite direction;


        the length of the trip is the same in both directions.



Under these conditions, the average rate is


    w%5Baverage%5D = %282%2Au%2Av%29%2F%28u%2Bv%29 = %282%2A5%2A1%29%2F%285%2B1%29 km/h = 10%2F6 km/h = 5%2F3 km/h = 1.6667 km/h.      ANSWER

Solved and thoroughly explained.



Answer by greenestamps(13195) About Me  (Show Source):
You can put this solution on YOUR website!


His downstream speed will be 3+2=5km/h; his upstream speed will be 3-2=1km/h.

The distances the two directions are the same; since his downstream speed is 5 times his upstream speed, his upstream trip will take 5 times as long as the downstream trip.

His average speed is then the weighted average of his two speeds:

%285%281%29%2B1%285%29%29%2F%285%2B1%29=10%2F6+=+5%2F3

ANSWER: His average speed for the trip is (5/3)km/hr