SOLUTION: A plane flew 720 mi with a steady 30 mi/hr tailwind. The pilot then returned to the starting point, flying against the same wind. If the round-trip flight took 10 hr, what was th

Question 971061:
A plane flew 720 mi with a steady 30 mi/hr tailwind. The pilot then returned to the starting point, flying against the same wind. If the round-trip flight took 10 hr, what was the plane's airspeed?

Found 2 solutions by checkley77, Alan3354:
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
D=RT
720=(R+30)+(R-30)]10
720=2R*10
720=20R
R=720/20
R=360 MI/HR. IS THE AIRSPEED OF THE AIRCRAFT
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!

A plane flew 720 mi with a steady 30 mi/hr tailwind. The pilot then returned to the starting point, flying against the same wind. If the round-trip flight took 10 hr, what was the plane's airspeed?
---------------
a = plane's airspeed
---
720/(a+30) + 720/(a-30) = 10
72/(a+30) + 72/(a-30) = 1
72(a-30) + 72(a+30) = a^2 - 900
144a = a^2 - 900
a^2 - 144a - 900 = 0
(a - 150)*(a + 6) = 0
a = 150 mi/hr

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