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Announcements

Announcements. Homework 3 and Homework 4 grades and solutions were already posted on Carmen.osu.edu website. Homework 5 (4.2, 4.6, 4.12, 4.24, 4.32, 4.40, 4.50, 4.60 in Chapter 4 ) is due Wednesday (10/17). Exam 1 is on Friday (10/19) in lecture. Exam 1 covers Chapters 1-4 and 6

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Announcements

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  1. Announcements • Homework 3 and Homework 4 grades and solutions were already posted on Carmen.osu.edu website. • Homework 5 (4.2, 4.6, 4.12, 4.24, 4.32, 4.40, 4.50, 4.60 in Chapter 4 ) is due Wednesday (10/17). • Exam 1 is on Friday (10/19) in lecture. • Exam 1 covers Chapters 1-4 and 6 • Bring a calculator (on cell phone or PDA calculators allowed), bring your ID, and one 8.5 X 11 sheet of notes (both sides) • Review for exam 1 on Thursday (10/18) in recitation.

  2. Problem solving---Chapter 4 • 4.5 The U.S. Department of Transportation reported the number of speeding-related crash fatalities for the 20 dates that had the highest number of these fatalities between 1994 and 2003 (Traffic Safety Facts, July 2005). • a. By looking at the histogram of this data set, which one (mean or median ?) do you think has a larger value? • b. Compute the mean and median number of speeding-related fatalities for these 20 days. Which one do you think is more representative of the sample and why? • c. Explain why it is not reasonable to generalize from this sample of 20 days to the other 345 days of the year.

  3. Problem solving---Chapter 4 • 4.10 Consider the following statement: More than 65% of the residents of Los Angeles earn less than the average wage for that city. Could this statement be correct? If so, how? If not, why not?

  4. Problem solving---Chapter 4 • 4.11 A sample consisting of four pieces of luggage was selected form among those checked at an airline counter, yielding the following data on x=weight (in pounds): • X1= 33.5, X2= 27.3, X3=36.7, X4=30.5 • Suppose that one more piece is selected; denote its weight by X5. Find a value of X5 such that sample mean = sample median.

  5. Problem solving---Chapter 4 • 4.35 Blood cocaine concentration (in milligrams per liter) was determined for both a sample of individuals who had died from cocaine-induced excited delirium and a sample of those who had died from a cocaine overdose without excited delirium. The accompanying data are consistent with summary values given in the paper “Fatal Excited Delirium Following Cocaine Use” (Journal of Forensic Sciences [1997]: 25-31):

  6. Questions for 4.35 • a. Determine the mean, median, quartiles and interquartile range for each of the two samples. • b. Compute the standard deviation for these two sample, which sample has more variability? • c. Are there any outliers in either sample? Any extreme outliers? • d. Construct a comparative boxplot, and use it as a basis for comparing and contrasting the two samples. (Hint: median marker, variability, whiskers etc.)

  7. Problem solving---Chapter 4 • 4.41 A student took two national aptitude tests. The national average and standard deviation were 475 and 100, respectively, for the first test and 30 and 8, respectively, for the second test. The student scored 625 on the first test and 45 on the second test. Use Z scores to determine on which exam the student performed better relative to the other test takers.

  8. Problem solving---Chapter 4 • 4.42 Suppose that your younger sister is applying for entrance to college and has taken the SATs. She scored at the 83rd percentile on the verbal section of the test and at the 94th percentile on the math section of the test. Because you have been studying statistics, she asks you for an interpretation of these values. What would you tell her?

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