## hw1

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## hw1

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- Pages:
- 5
- School:
- University of Wisconsin, Madison
- Course:
- Stat 324 - Intro Applied Stat for Engineers

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Homework 1 Due Wednesday June 27th at 4 pm Submit your homework on Canvas or to your TA s mailbox before to the due date time The mailboxes are to the left as you enter the Medical Science Center 1300 University Ave from the main University Ave entrance No late homework will be accepted for credit If a problem asks you to use R include a copy of the code and output Please edit your code and output to be only the relevant portions If a problem does not specify how to compute the answer you may use any appropriate method I may ask you to use R or manual calculations on exam so practice accordingly 1 If you wanted to estimate the mean height of all the students at a university which one of the following sampling strategies would be best Why Note that none of the methods are true simple random samples a Measure the heights of 50 students found in the gym during basketball intramurals b Measure the heights of the engineering majors c Measure the heights of the students selected by choosing the first name on each page of a campus phone book 2 A zoologist collected wild lizards in the Southwestern United States Thirty lizards from the genus Phrynosoma were placed on a treatmill and their speed measured The recorded speeds meters second the fastest time to run a half meter for the thirty lizards are summarized in the relative histogram below Courtesy of K Bonine 1 a Is the percent of lizards with recorded speed below 1 25 closest to 25 50 or 75 b In which interval are there more speeds recorded 1 5 1 75 or 2 2 5 c About how many lizards had recorded speeds above 1 meters second 3 In a sample of 20 men the mean height was 178 cm with standard deviation of 6 cm In a sample of 30 women the mean height was 164 cm with standard deviation of 6 cm If both samples were combined into one larger group a What is the mean height for the combined group b The standard deviation for the combined group would be hint do not do any calculations just try to sketch rough histograms for each sample separately and then one for the combined sample i ii iii iv Less than 6 cm Greater than 6 cm Equal to 6 cm Can not tell from the information given 4 After manufacture computer disks are tested for errors The table below gives the number of errors detected on a random sample of 100 disks Number of Defects Frequency 0 41 1 31 2 15 3 8 4 5 a What is the shape of the histogram for the number of defects observed in this sample b Calculate the mean and median number of errors detected on the 100 disks How do these values compare and is that consistent with what we would guess based on the shape c

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