Posted by Juliet on Sunday, May 5, 2013 at 10:57pm.
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  MathGuru, Monday, May 6, 2013 at 7:09pm
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 zscores:
z = (x  mean)/sd
x = 80 * .5 = ?
Once you have the zscore, find the probability using the ztable.
I hope this will help get you started.
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