A recent poll of over 2,000 adults was designed to answer the question "Are adults superstitious?" One survey item concerned the
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Answer:
The 99% confidence interval for the true percentage of all adults in the town that smoke is (0.1159, 0.2841).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence interval
, 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:
Of 150 adults selected randomly from one town, 30 of them smoke. This means that
99% confidence interval
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 99% confidence interval for the true percentage of all adults in the town that smoke is (0.1159, 0.2841).