Answer:
a) 272 used at least one prescription medication.
b) The 90% confidence interval estimate of the percentage of adults aged 57 through 85 years who use at least one prescription medication is (85.6%, 87.6%).
Step-by-step explanation:
Question a:
86.6% out of 3149, so:
0.866*3149 = 2727.
272 used at least one prescription medication.
Question b:
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 z-score that has a p-value of .
For this problem, we have that:
90% confidence level
So , z is the value of Z that has a p-value of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
For the percentage:
0.856*100% = 85.6%
0.876*100% = 87.6%.
The 90% confidence interval estimate of the percentage of adults aged 57 through 85 years who use at least one prescription medication is (85.6%, 87.6%).