SOLUTION: A boat traveled downstream a distance of 52 mi and then came right back. If the speed of the current was 5 mph and the total trip took 4 hours and 20 minutes, find the average spee

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Question 900323: A boat traveled downstream a distance of 52 mi and then came right back. If the speed of the current was 5 mph and the total trip took 4 hours and 20 minutes, find the average speed of the boat relative to the water.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

52/(r+5) + 52/(r-5) = 13/3

 52(r-5) + 52(r+5) = 13/3(r^2 - 25)

  104r = (13/3)(r^2-25)

  13r^2 -312r - 13*25 = 0

 r^2 - 24r - 25 = 0 

(r +1)(r-25) = 0,  r = 25mph