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The average age of statistics students nationwide is 22. The standard deviation is 2.5 years. Assume the age is a normally distributed variable.
Find the probability that one student selected at random is older than 23.
Find the probability that the mean age of a group of 16 students selected at random is bigger than 23

  • statistics -

    Z = (score - mean)/SD

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


    Z = (mean1 - mean2)/standard error (SE) of difference between means

    SEdiff = √(SEmean1^2 + SEmean2^2)

    SEm = SD/√(n-1)

    Since only one SD is provided, you can use just that to determine SEdiff.

    Use same table.

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