SOLUTION: (a) Find the minimal sample size required so that for a confidence interval, the maximal margin of error is (b) Based on this sample size and the distribution, can we assume th

Question 1201062: (a) Find the minimal sample size required so that for a confidence interval, the maximal margin of error is
(b) Based on this sample size and the distribution, can we assume that the distribution is approximately normal? Explain.

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
You are missing some information, but here is the approach.
error = z*sqrt(p*(1-p))/n
suppose z=1.96 for 95% CI
and suppose p=0.4 and n=50
then error=1.96*(sqrt(.24/50)
=0.1358
np and n(1-p) are both more than 10 so yes can assume normality.
note that the error for probability around 50% is about 1/sqrt(n).
This comes from using z=2 and p=0.5, Very useful to know this.
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