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)   (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


     =  =  km/h =  km/h =  km/h = 1.6667 km/h.      ANSWER

Solved and thoroughly explained.



Answer by greenestamps(13195)   (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:



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