Question 348379: A plane that can fly 200 mph in still air makes a 330 mile flight with a tail wind and returns, flying into the same wind. What is the speed of the wind if the total flying time is 3 1/2 hours?
Answer by checkley77(12844)   (Show Source):
You can put this solution on YOUR website! 3.5=330/(200+20)+330/(200-20)
3.5=330/220+330/180
3.5=1.5+1.833
3.5=3.333 DOESN'T EQUATE TO A PROOF.
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D=RT
T=D/R
3.5=330/(200+W)+330/(200-W)
3.5=[330(200-W)+330(200+W)]/(200+W)(200-W)
3.5=[66,000-330W+66,000+330W)/(40,000-W^2)
3.5=132,000/(40,000-W^2) CROSS MULTIPLY.
3.5(40,000-W^2)=132,000
140,000-3.5W^2=132,000
-3.5W^2=132,000-140,000
-3.5W^2=-8,000
W^2=-8,000/-3.5
W^2=2286
W=SQRT2286
W=47.81 MPH FOR THE HEAD WIND.
PROOF:
3.5=330/(200+47.81)+330/(200-47.81)
3.5=330/247.81+330/152.19
3.5=1.33+2.168
3.5~3.5
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