Suppose that 90% of all registered California voters
favor banning the release of information from exit polls
in presidential elections until after the polls in California
close. A random sample of 25 California voters is to be
selected.
a. What is the probability that more than 20 voters favor
the ban?
b. What is the probability that at least 20 voters favor
the ban?
c. What are the mean value and standard deviation of the
number of voters who favor the ban?
d. If fewer than 20 voters in the sample favor the ban, is
this at odds with the assertion that (at least) 90% of the
populace favors the ban? (Hint: Consider P(x " 20) when
p ! .9.)