Answer:
The 99% confidence interval for the proportion of drug-related deaths that were caused by legally prescribed drugs is (0.841, 0.943).
As a percentage, the confidence interval is (84.1%, 94.3%).
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 .
223 out of 250 deaths were caused by legally prescribed drugs.
This means 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 99% confidence interval for the proportion of drug-related deaths that were caused by legally prescribed drugs is (0.841, 0.943).
As a percent:
Multiply the proportions by 100%.
0.841*100% = 84.1%
0.943*100%= 94.3%
As a percentage, the confidence interval is (84.1%, 94.3%).