Answer:
The confidence limits for the proportion that plan to vote for the Democratic incumbent are 0.725 and 0.775.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
Of the 500 surveyed, 350 said they were going to vote for the Democratic incumbent.
This means that
80% confidence level
So , z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
The confidence limits for the proportion that plan to vote for the Democratic incumbent are 0.725 and 0.775.