{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

problemset7solution

# problemset7solution - PAM 2100 Spring 2009 Problem Set#7...

This preview shows pages 1–2. Sign up to view the full content.

PAM 2100 Spring 2009 Problem Set #7 Answer Key Total points: 10 #1) from the textbook: 7.38 Use df=1000. Round your final answer to four decimal places. (2 points) (The actual degree of freedom of this problem is 1406-1=1405. But since we do not have the t-values for this df in table D, we will use df=1000.) The value of t , for df=1000 and confidence level 99%, is 2.581. So the confidence interval is 0675 . 9 . 3 1406 98 . 0 * 581 . 2 9 . 3 ± = ± = ± = m x ( 1 point for the correct value of t , 1 point for the correct margin of error) (if someone uses n=1000 or 1001 by mistake, but the methods are otherwise correct, then take only 1 point off) #2) You will have complete sales information for last month in a week, but right now you have data from a random sample of 31 stores. The mean change in sales in the sample is x = 4.2 and the standard deviation of the changes in the sample is s = 10. Here are the null and alternative hypotheses: H 0 : μ = 0 H a : μ 0 a) Find the t-statistic. Round your answer to three decimal places, if necessary.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}