<PRE><B>Question 56780</B>
A plane flies 500 miles with the wind and 340 miles against the wind in the same length of time.  If the speed of the wind is 28mph, what is the speed of the plane in still air?
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Let speed of the plane be p mph.
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With the wind DATA:
distance= 500 miles ; rate = (p+28) mph ; time =d/r =500/(p+28) hrs. 
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Against the wind DATA:
distance=340 miles ; rate = (p-28) mph ; time = d/r = 340/(p-28) hrs
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EQUATION:
time with = time against
500/(p+28) = 340/(p-28)
25(p-28) = 17(p+28)
25p-700 = 17p+476
 8p=1176
p=147 mph (speed of the plane in still air)
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Cheers,
Stan H.</PRE>