SOLUTION: Horizons have a manufacturing plant located 300 mi from company headquarters. Their corporate pilot must fly from headquarters to the plant and back in 4 hrs. If there is a 20-mph

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Question 311941: Horizons have a manufacturing plant located 300 mi from company headquarters. Their corporate pilot must fly from headquarters to the plant and back in 4 hrs. If there is a 20-mph headwind going and a 20-mph headwind tailwind returning, how fast must the plane be able to travel in still air?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
300/x+20 + 300 / x-20 = 4
LCM (x+20)(x-20)
..
300(x-20)+300(x+20)= 4x^2-1600
300x-6000 +300x+6000= 4x^2-1600
4x^2-600x-1600=0
x^2-150x-400=0
Find X1 , X2 the roots of the equation
X1= 150+sqrt((-150)^2+1600) / 2
x= 152.6 mph