Question 1141559
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Let x be the rate of the jet stream.


Then the effective speed ("the ground speed") of the airplane flying with  the jet is

220 + x miles per hour.     (1)   



The effective speed ("the ground speed") of the airplane flying against  the jet is

220 - x miles per hour.     (2)   



The time equation is


    {{{1600/(220+x)}}} = {{{600/(220-x)}}}.



To solve it, cross-multiply


    1600*(220-x) = 600*(220+x)


and simplify step by step


    8*(220-x)    = 3*(220+x)

    8*220 - 8x   = 3*200 + 3x

    8*220 - 3*220 = 3x + 8x

    5*220         = 11x'

    x             = {{{(5*220)/11}}} = 5*20 = 100.


<U>ANSWER</U>.  The rate of the jet stream is  100 miles per hour.
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Solved.


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<U>The lesson to learn from this solution and the things to memorize are</U> :


<pre>
    1.  The effective speed of a plane flying with    a wind (with a jet) is the sum        of the two speeds.

    2.  The effective speed of a plane flying against a wind (against a jet) is the difference of the two speeds.

    3.  Write and use the time equation to solve the problem.
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