Big plane.
A six-passenger plane cruises in 180 mph at calm air. If the plane flies 7 miles with the wind in the same amount of time as it flies 5 miles against the wind, then what is the wind speed?
仲有呢條都係超難... 有冇人識答??? 勁趕... >___<
Algebra
2008-11-02 12:07 am
回答 (1)
2008-11-02 12:24 am
✔ 最佳答案
Let x miles/h be the wind speed.
Speed of the plane flying with the wind = (180 + x) miles/h
Speed of the plane flying against the wind = (180 - x) miles/h
Time taken = Distance / speed
7/(180 + x) = 5/(180 - x)
7(180 - x) = 5(180 + x)
1260 - 7x = 900 + 5x
-7x - 5x = 900 - 1260
-12x = -360
12x = 360
x = 30
Ans: The wind speed is 30 mph.
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