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Math Help - Easy Stats

  1. #1
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    Easy Stats

    Hi I really hope someone can help me here, I really am stuck and would like to know how to do them! 1.) A sample of 8 integers has a mean of 5 and a variance of 5.25. The integers are 1,3,5,7,4,5,p,q. Find p and q given that p
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  2. #2
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    Re: Easy Stats

    Sorry, given that p<q!
    Thank you so much in advance!
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  3. #3
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    Re: Easy Stats

    Use first the definition of mean, that will give p = q = 15.
    Then we are given variance I
    Use the formula attached to find variance. now you will have two equations in two variables just solve the equations to get p and q. Easy Stats-8-jun-13.png
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  4. #4
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    Re: Easy Stats

    Hi thanks for the reply! that's what I did. Ended up with 2 equations, p^2+q^2-10p-10q = -8 and p+q = 15. Got stuck there...
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  5. #5
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    Re: Easy Stats

    Remember a^2 +b^2 = ( a + b)^2 - 2ab
    Also we can write - 10 p -10 q = -10 ( p + q )
    Plu in th value of p + q
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  6. #6
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    Re: Easy Stats

    There appears to be something wrong in your equation.
    From variance equation you should get
    p^2 + q^2 - 10(p+q) = -33
    OR (p+q)^2 - 2pq -10 (p+q) = -33
    (15)^2 - 2pq -150 = -33
    225 -2pq - 150 = -33
    2pq = 108 OR pq = 54
    Now u have. Two equations
    P + q = 15 and pq = 54
    Solve the see and you will get two values of p as 9 and 6
    since p < q select p = 6 And q will be 9
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  7. #7
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    Re: Easy Stats

    Yes, there was a mistake in my working. Thank you so so so much, really!!
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  8. #8
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    Re: Easy Stats

    Yes, there was a mistake in my working. Thank you so so so much, really!!
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