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Math Help - Normal distribution, help please

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    Normal distribution, help please

    OK I have a normal distribution N(m,v) (mean and variance unknown) I have been given the values of the lower and upper quartiles of this distribution, they are 2/3 and 4. How do I find the mean and variance with just this information?
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    Quote Originally Posted by Jeff1987 View Post
    OK I have a normal distribution N(m,v) (mean and variance unknown) I have been given the values of the lower and upper quartiles of this distribution, they are 2/3 and 4. How do I find the mean and variance with just this information?
    Use tables or technology to find the value of a and b such that \Pr(Z > a) = 0.25 and \Pr(Z < b) = 0.25.

    From Z = \frac{X - \mu}{\sigma}:

    a = \frac{4 - m}{\sigma} .... (1)

    b = \frac{\frac{2}{3} - m}{\sigma} .... (2)

    Solve equations (1) and (2) simultaneously for m and n.
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