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Math Help - help!

  1. #1
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    help!

    "1. A train travels 35 miles per hour for 170 minutes
    How far will the train travel in this time?

    A car completed this same journey in 60% of the time the train took
    Find the average speed of the car in mph

    2. Y is inversely proportional to X. When Y=4, X=3.
    Find an equation linking X and Y.

    If X = 6 find the value of Y. (Hint, use the equation you've found above)"

    there's no words to explain how confused i am right now
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  2. #2
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    Quote Originally Posted by amy15 View Post
    2. Y is inversely proportional to X. When Y=4, X=3.
    Find an equation linking X and Y.

    If X = 6 find the value of Y. (Hint, use the equation you've found above)"

    there's no words to explain how confused i am right now
    "Y is inversely proportional to X"
    -\,\, Y = \frac{k}{X^2}

    "When Y=4, X=3"
    -\,\, 4 = \frac{k}{3^2} \Rightarrow k = 36

    "Find an equation linking X and Y."
    -\,\, Y = \frac{36}{X^2}

    "If X = 6 find the value of Y. (Hint, use the equation you've found above)"
    -\,\, Y = \frac{36}{6^2}\Rightarrow Y = 1

    "there's no words to explain how confused i am right now "
    -\,\,\text{Oops....At least, I hope you are not now}
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  3. #3
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    thanks! i'm not so confused anymore
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  4. #4
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    Question 1

    1: \text{distance}=\text{speed}\times\text{time}

    In this case, the speed is 35 mph, and the time is 170 minutes ( {170}\div{60} hours)

    so the distance that the train travels is 35\times (170\div60)= 99.167 miles.

    The car traveled 99.167 miles in 60% of 170 minutes.
    So it travelled 99.167 miles in \frac{170}{100}\times60=102 minutes ( 102\div60=1.7 hours)

    \text{speed}=\frac{\text{distance}}{\text{time}}

    Therefore the average speed is \frac{99.167}{1.7}=58.334 mph
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