Question 1044819: In a survey of 628 males ages 18-64, 393 say they have gone to the dentist in the past year.
Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals.
The 90% confidence interval for the population proportion p is? (Round to three decimal places as needed.)
The 95% confidence interval for the population proportion p is? (Round to three decimal places as needed.)
Interpret your results of both confidence intervals.
A.With the given confidence, it can be said that the sample proportion of males ages 18-64 who say they have gone to the dentist in the past year is between the endpoints of the given confidence interval.
B.With the given confidence, it can be said that the population proportion of males ages 18-64 who say they have gone to the dentist in the past year is between the endpoints of the given confidence interval.
C.With the given confidence, it can be said that the population proportion of males ages 18-64 who say they have gone to the dentist in the past year is not between the endpoints of the given confidence interval.
Which interval is wider?
The 90% confidence interval
The 95% confidence interval
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Using a calculator and a 1 proportion Z-interval, the point estimate is 393/628=0.626
(0.594,0.658) is the 90% CI
(0.588,0.664) is the 95% CI
The correct choice is B. CI are statements about the population. We know what the sample was; we are 90% or 95% confident that the true proportion, which we don't know and never will know, is in the interval constructed. It is not a probability.
The 95% interval is wider, and one needs a wider interval if one wants to be more confident. One way to remember that is one needs a 100% interval if one wants to be 100% confident.
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