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Practice_Midterm_solutions - Practice Midterm Solutions I...

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Practice Midterm Solutions I. Short answer questions 1. A stemplot of a set of data is roughly symmetric, but the data do not even approximately follow the 68-95-99.7 rule. We conclude that the data are A) Normal, but they are not standard normal. B) Standard normal. C) Not normal. D) Not enough information to determine whether it is standard normal. Answer: C 2. A high school guidance counselor wants to study the later earnings of the class of 1990. The high school had 800 graduates in the class of 1990; among them, 400 obtained college degrees and the other 400 did not. In the year 2000, the counselor randomly selects 20 individuals from among those who obtained college degrees, and another 20 individuals among those who didn’t obtain college degrees. Earnings data is collected on these 40 selected individuals. This study is: A) A designed experiment, in which the “treatment group” receives a college degree, and the “control group” gets no college degree. B) Based on “anecdotal evidence”, and hence is not reliable. C) An observational study, in which the 40 selected individuals are a Simple Random Sample. D) An observational study. However, the 40 selected individuals are not a Simple Random Sample. Answer: D 3. Following the previous question. From the data collected, the high school guidance counselor finds that the average earnings of the 20 individuals who didn’t obtain college degrees is $23,000. The value $23,000 is
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4. Volunteers for a research study were divided into three groups. Group 1 listened to Western religious music, group 2 listened to Western rock music, and group 3 listened to Chinese religious music. The blood pressure of each volunteer was measured before and after listening to the music, and the change in blood pressure (blood pressure before listening minus blood pressure after listening) was recorded. What could we do to explore the relationship between type of music and change in blood pressure? A) See if blood pressure decreases as type of music increases by examining a scatterplot. B) Make a histogram of the change in blood pressure for all of the volunteers. C) Make side-by-side boxplots of the change in blood pressure, with a separate boxplot for each group.
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