SOLUTION: a plane flies 500 miles with the wind and 300 miles against the wind in the same length of time. If the speed is 30mph, what is the speed of the plane?

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Question 208453: a plane flies 500 miles with the wind and 300 miles against the wind in the same length of time. If the speed is 30mph, what is the speed of the plane?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
a plane flies 500 miles with the wind and 300 miles against the wind in the same length of time.
If the wind speed is 30 mph, what is the speed of the plane?
;
Let s = speed of the plane in still air
then
(s+30) = speed with the wind
and
(s-30) = speed against the wind
:
Write time equation: Time = dist%2Fspeed
:
Time with = time against
500%2F%28s%2B30%29 = 300%2F%28s-30%29
Cross multiply:
500(s-30) = 300(s+30)
:
500s - 15000 = 300s + 9000
:
500s - 300s = 9000 + 15000
:
200s = 24000
s = 24000%2F200
s = 120 mph, plane in still air
:
:
:
Check solution, find the times:
500/150 = 3.33
300/90 = 3.33