Ch2ex - statistical problems PDF

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Chapter 2 Exercises

1. In a frequency distribution the categories must A. Be mutually exclusive. B. Have at least 5 observations. C. Be of the same size. D. Be of nominal scale. The correct answer is a. However c is also very desirable. 2. To determine the class interval A. Divide the class frequencies in half. B. Divide the class frequency by the number of observations. C. Find the difference between consecutive lower class limits. D. Count the number of observations in the class. The correct answer is c. You could also find the difference between consecutive upper class limits.

3. The class frequency is A. The number of observations in each class. B. The difference between consecutive lower class limits. C. Always contains at least 5 observations. D. Usually a multiple of the lower limit of the first class. The correct answer is a. That's its definition. 4. A research organization is making a study of the selling price of home computers. There are 45 computers in the study. How many classes would you recommend? A. 10 B. 20 C. 6 D. 3 The correct answer is c because the fifth power of 2 is only 32, but the sixth power of 2 is 64 and 45 is between them. 5. To find the class midpoint A. Divide the class interval in half and add the result to the lower limit. B. Find the difference between consecutive lower limits. C. Count the number of observations in the class. D. Divide the class frequency by the number of observations. The correct answer is a. because that value is most representative of all values in the class. 6. Which of the following is not a guideline for a frequency distribution? A. Avoid open-ended classes. B. Have more than 5 but less than 15 classes. C. Make the lower limit of the first class a multiple of the class interval. D. Have more than 5 observations in each class. The correct answer is d. You really can't control how many observations will fall in a class.

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Chapter 2 Exercises

7. To convert a frequency distribution to a relative frequency distribution A. Find the difference between consecutive lower class limits. B. Divide the class frequency by the total number of observations. C. Divide the lower limit of the first class by the class interval. D. Multiple the class frequency by 100. The correct answer is b. The word "relative" implies it has a relation to the total number of observations 8. In a line chart the horizontal axis: A. Is usually in dollars. B. Usually involves time, such as hours or months. C. Is usually shown with a dotted line. D. Is usually reported as a percent. The correct answer is b. The other answers do not make any sense. 9. The difference between a histogram and a frequency polygon is A. The frequency polygon is reported as a percent. B. The histogram employs bars whereas the midpoints are connected for a frequency polygon. C. Bars cannot be adjacent in a histogram. D. Open-ended classes can be accommodated with a frequency polygon. The correct answer is b. The other answers are just "gorilla dust."

10. In a cumulative frequency polygon A. The class frequencies are converted to a percent. B. There must be at least 5 observations in each class. C. We add the class frequencies starting with the first class. D. All of the above. The correct answer is c. Cumulative is a word, which implies adding. 11. Refer to the following information on the number of units assembled per shift at Acme Assembly, Inc.

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Chapter 2 Exercises

The class interval is: A. 10 B. 25 C. 9 D. None of the above. The correct answer is a. 10, found by 30 20.

12. Refer to the following information on the number of units assembled per shift at Acme Assembly, Inc.

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The frequency for the third class is A. 200 B. 51 C. 10 D. None of the above.

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