Math- Statistics

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Suppose 60% of adults have a college degree. If I take a random sample of 80 adults, what is the probability at least 50% of them have a college degree?

  • Math- Statistics -

    Use the normal approximation to the binomial distribution.

    mean = np = 80 * .6 = ?

    standard deviation = √npq = √(80 * .6 * .4) = ?

    Calculate. (Note: q = 1 - p)

    Next use z-scores:

    z = (x - mean)/sd

    x = 80 * .5 = ?

    Once you have the z-score, find the probability using the z-table.

    I hope this will help get you started.

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