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File Edit View History Bookmarks Tools Window Help Firefox Do Homewo On https://www. athxl.com /Student/PlayerHomework.aspx?homeworkld-329876179&questionld; 9&flushed; cld 3633804 yes Homework: Homework #5 (Chapter 6) nstructor created question 3 of 12 pt HW Score: 60% 8 of 30 pt 11 of 11 complete Periodically, a town water department tests the drinking water of homeowners for contaminants such as lead. The lead levels in Lead (mg /L) water specimens collected for a sample of 10 residents o the town are shown 32 32 3.3 4.03 0.975 4.41 0.697 1) Use the Powerpoint presentation instructions on Moodle to determine whether you have access to the Microsoft Excel Data Analysis Toolpak on your computer. If not, you will need to complete this assignment in one of the univers computer labs. Open or download the link "Locating the MS Excel Data Analysis Toolpak." 2) Use the "Descriptive Statistics" tool in the Microsoft Excel Data Analysis Toolpak to generate the information you will need to complete the following questions. The Powerpoint presentation "Using the Descriptive Statistics on Moodle will show you an example for using this too Tool h a. Fill in the following table based on the descriptive statistics generated by MS Excel round each answer to four decimal places as needed) Sample mean Sample standard deviation Sample variance b. Use the MS Excel Descriptive Statistics to construct a 99% confidence interval for the mean lead level in water specimens from the town. NOTE: you will need to look up the critical value on the probability table in the textbook since Excel does not provide this information. Critical value (Round to three decimal places as needed. Confidence Interval: D (Round to three decimal places as needed.) c. Interpret the interval in the words of the problem. The confidence interval means that we are confident that the true for all the people in is in the interval. d. Discuss the meaning of the phrase, "99% confident." dit fields, th k Check A Clear Check Answer Save 2/12/16 7:36 PM Overview View Instructor Tip Ask My Instructor Print

Explanation / Answer

Sample mean = 2.9152

sample standard deviation = 3.9739

sample variance = 15.7918

b) critical value (t with 9 df ) = 3.250

confidence interval = (-1.169,6.999)

c)The confidence interval means that we are 99% confidenct that the true mean lead level for all the people in (-1.169,6.999) is the interval

d.If we repeatedly take samples , 99% of the sample would contain this interval.

Descriptive statistics Lead   count 10 mean 2.91520 sample variance 15.79181 sample standard deviation 3.97389 standard error of the mean 1.25665 confidence interval 99.% lower -1.16872 confidence interval 99.% upper 6.99912    half-width 4.08392 Critical value 3.249836

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