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Math Help - problem of normal distribution

  1. #1
    kin
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    problem of normal distribution



    i set up the equation P[ (X1+X2+...+X5)/5 < K ] = 0.3
    then P[ z < ( 5K-(20)(5) )/ √(4)(5)] = 0.3
    am i right???
    if i am wrong, show me how to solve it please...
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  2. #2
    Flow Master
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    Quote Originally Posted by kin View Post


    i set up the equation P[ (X1+X2+...+X5)/5 < K ] = 0.3
    then P[ z < ( 5K-(20)(5) )/ √(4)(5)] = 0.3
    am i right???
    if i am wrong, show me how to solve it please...
    Note that \overline{X} ~ Normal \left(\mu = 20, \sigma^2 = \frac{4}{5}\right).

    So \Pr\left( Z < \frac{K - 20}{\frac{2}{\sqrt{5}}}\right) = 0.3.

    So, although it's a bit hard to tell, it looks like you're right.
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