Question 747346: Political Survey A political analyst found that 43% of 300 Republican voters feel that the federal government has too much power. Find the 95% confidence interval of the population proportion of Republican voters who feel this way.
A sample of 25 novels has a standard deviation of 9 pages. Find the 95% confidence interval of the population standard deviation.
Answer by mikeebsc(26)   (Show Source):
You can put this solution on YOUR website! I will get to problem 1 if I have time tonight, otherwise I recommend re-posting it alone, and in the future posting each problem separately :)
Problem 2:
The formula for a confidence interval is the estimate -+ the margin of error.
To find the margin of error we use the formula:
E=Zc(Std. Dev./square root of sample size (Zc=Z critical and there are tables that show the values for 80%, 90%, 95%, and 99% in most textbooks and on the internet)
For a 95% confidence interval, Zc=1.96 SO:
E=1.96(9/square root of 25) = 3.528 SO: The confidence interval is:
(9-3.528),(9+3.528)
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