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Math Help - Standard Deviation Help needed!

  1. #1
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    Standard Deviation Help needed!

    I'm really stumped by this question since the 1st standard deviation would be 0.41, not 0.40. . .


    An important measure of the performance of a locomotive is it's "adhesion" which is the locomotive's pulling force as a multiple of it's weight. The adhesion of one 4400-horsepower diesel locomotive model varies in actual use according to a normal distribution with mean of 0.37 and standard deviation of 0.04. What proportion of adhesions measured in use are higher than 0.40?

    Thanks for the help!
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  2. #2
    Master Of Puppets
    pickslides's Avatar
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    Have you tried?

    \displaystyle P(X>0.4) = P\left(Z>\frac{0.4-0.37}{0.04}\right)=\dots
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