Example 1: ( Example 11.3 in text (Containers) -- cont.)


Example 2: ( Political Surveys,  Inc.)  Political Surveys, Inc.  (PSI)
is a firm that specializes in voter polls and surveys designed to keep
political  office  seekers  informed of their   position  in the race.
Using 500 telephone  surveys, interviewers  ask registered voters  who
they would vote for if the election were held today.  By computing the
sample   proportion for a  particular  candidate, Political Surveys is
able  to estimate  the  proportion of  the  population  that favor the
candidate.  PSI wants to  develop  a 95% confidence interval  estimate
for  the proportion of  the registered voters  in  the population that
favor the candidate.

Data: In a recent election campaign,  Political Surveys found that 220
of 500 registered voters favored a particular candidate.