statistics

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The duration of time it takes General Motors to build a car is normally distributed with a mean of 31 hours and a standard deviation of 2 hours.
a) What is the probability that a single car, selected at random,
will take between 28 and 34 hours?
b) What is the probability that the mean of the times for a sample
of 25 cars will be between 28 and 34 hours?

  • statistics -

    a) Z = (score-mean)/SD

    Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

    b) Z = (score-mean)/SEm

    SEm = SD/√n

    Use the table.

  • statistics -

    27272

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