random variable x is normally distributed with mean mu87 and standard deviation sigma5. Find the indicated probability?

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  • 3 months ago
    Favourite answer

    P(x < 80) => P(z < (80 - 87)/5)

    i.e. P(z < -1.4)

    By symmetry this is P(z > 1.4)

    Hence, 1 - P(z < 1.4)

    From normal tables we get:

    1 - 0.91924 => 0.08076

    so, 0.0808...to 4 d.p.

    i.e. about 8.1%

    :)>

  • rotchm
    Lv 7
    3 months ago

    Transform to z space via z = (x-avg)/std. Then, lookup in the z table.

    Done!

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