Question 137231: the speed of the airplane in still air is 186mph. the plane travals 538 mi againt the wind and 1415 mi with the wind in a total time of 12 hr. what is the speed of the wind
Answer by checkley77(12844)   (Show Source):
You can put this solution on YOUR website! 538/(186-x)+1415/(186+x)=12
[538(186+x)+1415(186-x)]/(186-x)(186+x)=12 now cross multiply
12(186-x)(186+x)=538(186+x)+1415(186-x)
12(34,596-x^2)=100,068+538x+263,190-1415x
415,152-12x^2=363,258-877x
-12x^2-877x+415,152-363,258=0
-12x^2-877x+51,894=0
using the quadratic equation we get:
x=(877+-sqrt[-877^2-4*-12*51,894])/2*-12
x=(877+-sqrt[769,129+2,490,912])/-24
x=(877+-sqrt[3,260,041)/-24
x=(877+-1,805.5583)/-24
x=(877-1,805.5583)/-24
x=-928.5583/-24
x=38.69 mph is the speed of the wind.
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