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Math Help - Standard deviation

  1. #1
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    Standard deviation

    The lifetime of a lightbulb is normally distributed with a mean life of 1000 hours and a standard deviation of 30 hours. Find the probability that a randomly selected lightbulb lasts longer than 1045 hours.

    Using the bell curve, I get 6.7%, but I'm not sure if I'm right. Please let me know what the answer is and explain please!
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  2. #2
    Master Of Puppets
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    correct as P(Z>1.5) = .0668

    How is this trigonometry?
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