2 answers:
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Answer:
The confidence interval at the 99% confidence level for the proportion of all adult Americans who believe in astrology is (0.2251, 0.2749). This means that we are 99% sure that the true proportion of all adult Americans who believe in astrology is in this interval.
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 .
For this problem, we have that:
99% 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 interval at the 99% confidence level for the proportion of all adult Americans who believe in astrology is (0.2251, 0.2749). This means that we are 99% sure that the true proportion of all adult Americans who believe in astrology is in this interval.