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Math Help - Help please, few problems

  1. #1
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    Help please, few problems

    1.) 4k+2
    ....____ > 2 Had to put periods in to keep it in place, but it is 4k+2 diveded by 5 is greater then 2, how do I solve that?
    .......5

    2.) A person'as body mass index is given by the expression Weight/h2 where W is the weight in kilogrammes and h is the height in meters. A normal BMI is at least 18.5 but less than 25. If a ballplayer is 2 metres tall, then what can his weight be if his BMI is normal? Hint: since you know his height, first calculate his h2, Now you have an expression for his BMI with only one varialbe in it, this is supposed to be at least 18.5 but less than 25. Any help on this would would be great too.

    Thanks in advance, You guys rock!
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  2. #2
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    Quote Originally Posted by MathMack View Post
    1.) 4k+2
    ....____ > 2 Had to put periods in to keep it in place, but it is 4k+2 diveded by 5 is greater then 2, how do I solve that?
    .......5

    2.) A person'as body mass index is given by the expression Weight/h2 where W is the weight in kilogrammes and h is the height in meters. A normal BMI is at least 18.5 but less than 25. If a ballplayer is 2 metres tall, then what can his weight be if his BMI is normal? Hint: since you know his height, first calculate his h2, Now you have an expression for his BMI with only one varialbe in it, this is supposed to be at least 18.5 but less than 25. Any help on this would would be great too.

    Thanks in advance, You guys rock!

    Question 2: First of all you know that his height is 2m, and his BMI equals his weight divided by height squared. You also know that his BMI has to be between 18.5 and 25.

    W/2^2 =BMI
    W/4 =BMI

    Next you have to rearrange the equation to find his weight:
    W= 4*BMI

    Can you work it out from here?
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  3. #3
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    No i'm really lost, could you help me out more, Appreciate it! Thanks for your help
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  4. #4
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    Let W equal weight, and H equal height.

    W/H^2 =BMI
    W/2^2 =BMI

    Now rearrange the question
    H^2*BMI =W
    4*BMI =W

    The lowest his BMI can be is 18.5:
    4*18.5 =W
    4*18.5 =74
    So, the lowest weight he can be is 74kg.

    The highest his BMI can be is 25:
    4*25 =W
    4*25 =100
    So the highest weight he can be is 100kg.

    He must weigh between 74kg and 100kg.

    Does this make sense? Im not really good at explaining things, sorry. Maybe someone else can explain it better.
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  5. #5
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    Quote Originally Posted by MathMack View Post
    1.) 4k+2
    ....____ > 2 Had to put periods in to keep it in place, but it is 4k+2 diveded by 5 is greater then 2, how do I solve that?
    .......5

    ...
    Hello,

    I'll show you how to get the solution step by step:

    \frac{4k+2}{5}>2 Multiply by 5. Since 5 is positive the ">"-sign doesn't change.

    4k+2 > 10 Subtract 2 at both sides

    4k > 8 Divide by 4. Since 4 is positive the ">"-sign doesn't change

    \boxed{k>2} That's it!
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