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Math Help - summer school T-T

  1. #1
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    Thumbs down summer school T-T

    i need help with some problems
    i will add more to this post

    for each direct variation, find the constant of variation. then find the value of y when x = -5

    y=2 when x=7


    AVIATION
    a speed of 60 mi/h is equal to a speed of 88 ft/s find the speed in mph of an aircraft travaling 1000ft/s
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  2. #2
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    1. I'm going to assume that y varies directly to x.

    If y varies directly to x, then
    y = k \cdot x

    K is the constant of variation. Find constant of variation using the numbers given in the question, then replace in the equation above. Then find y when x = -5.

    2.
    Given:
    v = \frac{60\ mi}{1 h} = \frac{88\ ft}{1\ s}

    Using this given relation, you can find out how many feet are there in 1 mile:

    \frac{60\ mi}{3600\ s} = \frac{88\ ft}{1\ s}

    60\ mi = \frac{88\ ft \cdot 3600\ \not{s}}{1\ \not{s}}

    1\ mi = \frac{88\ ft \cdot 3600}{60} = 5280\ ft

    \frac{1000\ ft}{1\ s} = \frac{ ?\ mi}{ ?\ h}

    Now, let's divide this into two parts.
    a. Find how many miles are there in 1000 ft.
    b. Find how how many hours in a second.
    b. Substitute.

    a.
    ? mi = \frac{1000}{5280}

    b. There are 3600 seconds in an hour. So how many hours are there in one second?
    \frac{1}{3600}

    Can you continue?
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  3. #3
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    idk
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  4. #4
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    \frac{1000\ ft}{1\ s} = \frac{\frac{1000}{5280}\ mi}{\frac{1}{3600}\ s}

    I'll leave the computations for you. :-)
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  5. #5
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    Last edited by zachi2; July 17th 2008 at 06:21 AM.
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