SOLUTION: a plane flies 495 miles with the wind and 440 miles against the wind in the same length of time. if the speed of the wind is 10 mph, find the speed of the plane in still air
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Question 912726: a plane flies 495 miles with the wind and 440 miles against the wind in the same length of time. if the speed of the wind is 10 mph, find the speed of the plane in still air Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! r*t=d
(r-10)*t=440
(r-10*t=440
r*t-10*t=440
(r+10)*t=495
r*t+10*t=495
r*t-10*t=440
add
2r*t=935
r*t=935/2
r*t=467.5
ok
r*t-10*t=440
467.5-10*t=440
467.5-440=10*t
27.5=10*t
27.5/10=t
2.75=t
t=2.75 hour time
r*2.75=467.5
r=467.5/2.75
r=170.0 mph rate still air
check
(r+c)*t=495
(170+10)*2.75=495
(180)*2.75=495
495.0=495
(r-c)*t=440
(170-c)*t=440
(170-10)*2.75=440
160*2.75=440
440.0=440
ok
