Portland State University (United States)

STAT 243 BU - Version A Name: Midterm Exam You may use one page of notes (front and back is Okay) prepared by yourself and a calculator. However, class notes and textbooks are not allowed. This is an hour and 50 minutes exam. Use a pencil and an eraser in order to mark exactly one choice on your scantron for each problem. Submit BOTH your scantron form and exam. 1. To determine the average salary of professors at Portland State University, the faculty were divided into the following groups: instructors, assistant professors, associate professors, and professors. Twenty faculty members from each group were selected for the study. This represents what type of sampling method? (a) random sampling (b) systematic sampling (c) stratified sampling (d) cluster sampling 2. At a computer facility, every 200 th computer chip is inspected for defects. This is an example of what type of sampling method? (a) random sampling (b) systematic sampling (c) stratified sampling (d) cluster sampling 3. Which of the following should not be done when constructing a frequency distribution? (a) Select the number of classes desired (b) Find the range (c) Use classes that are unequal in width (d) Use classes that are mutually exclusive 4. What is a graph which represents data which occurs over a specific period of time called? (a) time series graph (b) pictograph (c) histogram (d) pie graph Spring 2015 1 Portland State University

5. A frequency distribution is listed below. Limits f 46 – 52 8 53 – 59 10 60 – 66 12 67 – 73 7 74 – 80 2 How many items are in this sample? (a) 12 (b) 8 (c) 39 (d) 35 6. The following information shows the colors of cars preferred by customers. Colors Frequency Red 50 White 60 Blue 40 Tan 20 Green 10 How many degrees will the green represent in a pie graph? (a) 30 o (b) 20 o (c) 40 o (d) 50 o 7. If you look at the coins in your pocket and state that you have more dimes than any other coin, what measure of central tendency are you using? (a) mode (b) mean (c) midrange (d) median Spring 2015 2 Portland State University

Use the following sample data to answer Questions 12 and 13: 120, 117, 191, 115, 130, 125, 140, 126 12. What is the median of this data set? (a) 125 (b) 126 (c) 125.5 (d) 122.5 13. What is the interquartile of this data set? (a) 16.5 (b) 10 (c) 23 (d) 14.5 14. The first test in Introductory Statistics had a mean 82 with a standard deviation 15. If a student made a 75 on the test, what is the corresponding z-score? (a) -0.58 (b) -0.47 (c) 0.47 (d) 0.82 15. For a sample of size 5, if x 1 - ¯ x = - 5, x 2 - ¯ x = 9, x 3 - ¯ x = - 7, x 4 - ¯ x = - 2, then the sample standard deviation is (Hint: Figure x 5 - ¯ x out first. Think about the role of the sample mean) (a) 5.639 (b) 6.782 (c) 6.066 (d) 6.305 16. A die is rolled. If an odd number is obtained on the first roll, a coin is tossed. If an even number is obtained on the first roll, the die is rolled again. Using a tree diagram, how many outcomes are possible? (a) 12 (b) 6 (c) 8 (d) 24 Spring 2015 4 Portland State University

17. A license plate must have 3 letters, followed by three digits. The first letter must be a W. How many different license plates are available? (Repetitions are allowed) (a) 676 , 000 (b) 576 , 000 (c) 476 , 000 (d) 376 , 000 18. There are 3 blue balls, 5 red balls, and 4 white balls in a bag of balls. If a person selects two of the balls, what is the probability that the second one is blue given that the first one was white? (a) 2 11 (b) 1 11 (c) 3 11 (d) 5 12 19. If 30 tickets are sold and 2 prizes are to be awarded, find the probability that one person will win both prizes if that person buys exactly 2 tickets. (a) 1 435 (b) 1 870 (c) 1 970 (d) 1 4060 Spring 2015 5 Portland State University

23. The relative frequency of a class is computed by (a) dividing the cumulative frequency of the class by n (b) dividing n by cumulative frequency of the class (c) dividing the frequency of the class by n (d) dividing the frequency of the class by the number of classes For Problems 24 - 28 use the following information. Employee Years of Employee Number Gender Department Experience Rank (1–10) Yearly Salary 23450 Male Accounting 15 10 $52 , 443 . 00 34568 Female IT 24 7 $111 , 239 . 00 23123 Female Personnel 20 4 $84 , 473 . 00 23007 Male Finance 9 1 $ 47 , 519 . 00 24. Employee Number is an example of data. (a) nominal (b) ordinal (c) interval (d) ratio 25. Gender is an example of data. (a) nominal (b) ordinal (c) interval (d) ratio 26. Years of Experience is an example of data. (a) nominal (b) ordinal (c) interval (d) ratio 27. Employee Rank is an example of data. (a) nominal (b) ordinal (c) interval (d) ratio 28. Yearly Salary is an example of data. (a) nominal (b) ordinal (c) interval (d) ratio Spring 2015 7 Portland State University