0.2 Practice tests (1-4) and final exams  (Page 3/36)

23 . A researcher analyzes the results of the SAT (Scholastic Aptitude Test) over a five-year period and finds that male students on average score higher on the math section, and female students on average score higher on the verbal section. She concludes that these observed differences in test performance are due to genetic factors. Explain how lurking variables could offer an alternative explanation for the observed differences in test scores.

24 . Explain why it would not be possible to use random assignment to study the health effects of smoking.

25 . A professor conducts a telephone survey of a city’s population by drawing a sample of numbers from the phone book and having her student assistants call each of the selected numbers once to administer the survey. What are some sources of bias with this survey?

26 . A professor offers extra credit to students who take part in her research studies. What is an ethical problem with this method of recruiting subjects?

2.1: stem-and leaf graphs (stemplots), line graphs, and bar graphs

Use the following information to answer the next four exercises. The midterm grades on a chemistry exam, graded on a scale of 0 to 100, were:
62, 64, 65, 65, 68, 70, 72, 72, 74, 75, 75, 75, 76,78, 78, 81, 83, 83, 84, 85, 87, 88, 92, 95, 98, 98, 100, 100, 740

27 . Do you see any outliers in this data? If so, how would you address the situation?

28 . Construct a stem plot for this data, using only the values in the range 0–100.

29 . Describe the distribution of exam scores.

2.2: histograms, frequency polygons, and time series graphs

30 . In a class of 35 students, seven students received scores in the 70–79 range. What is the relative frequency of scores in this range?

Use the following information to answer the next three exercises. You conduct a poll of 30 students to see how many classes they are taking this term. Your results are:
1; 1; 1; 1
2; 2; 2; 2; 2
3; 3; 3; 3; 3; 3; 3; 3
4; 4; 4; 4; 4; 4; 4; 4; 4
5; 5; 5; 5

31 . You decide to construct a histogram of this data. What will be the range of your first bar, and what will be the central point?

32 . What will be the widths and central points of the other bars?

33 . Which bar in this histogram will be the tallest, and what will be its height?

34 . You get data from the U.S. Census Bureau on the median household income for your city, and decide to display it graphically. Which is the better choice for this data, a bar graph or a histogram?

35 . You collect data on the color of cars driven by students in your statistics class, and want to display this information graphically. Which is the better choice for this data, a bar graph or a histogram?

2.3: measures of the location of the data

36 . Your daughter brings home test scores showing that she scored in the 80 ^th percentile in math and the 76 ^th percentile in reading for her grade. Interpret these scores.

37 . You have to wait 90 minutes in the emergency room of a hospital before you can see a doctor. You learn that your wait time was in the 82 ^nd percentile of all wait times. Explain what this means, and whether you think it is good or bad.