Name: Class: Date: 1. Use Figure 2-1. For this density curve, what percent of the observations lie above 4? a. 20% b. 25% c. 50% d. 75% e.

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1 Name: Class: Date: Chapter 2 Review Multiple Choice Identify the choice that best completes the statement or answers the question. EXPLAIN YOUR ANSWERS AND SHOW YOUR WORK. Figure Use Figure 2-1. For this density curve, what percent of the observations lie above 4? a. 20% b. 25% c. 50% d. 75% e. 80% 2. You are told that your score on an exam is at the 85 percentile of the distribution of scores. Which of the following is a correct interpretation of this information? a. Your score was lower than approximately 85% of the people who took this exam. b. Your score was higher than approximately 85% of the people who took this exam. c. You answered 85% of the questions correctly. d. If you took this test (or one like it) again, you would score as well as you did this time 85% of the time. e. 85% of the people who took this test earned the same score you did. 3. A score s percentile is a measure of a. center b. spread c. relative location d. skew e. relative frequency 1

2 Name: 4. Consider the following cumulative relative frequency graph of the scores of students in an introductory statistics course: A grade of C or C+ is assigned to a student who scores between 55 and 70. The percentage of students who obtained a grade of C or C+ is a. 15% b. 20% c. 25% d. 30% e. 50% 5. A standard score describes a. How much skew there is in a distribution b. How much spread there is in a distribution c. How far apart the mean and median of a distribution are. d. How far a particular score is from the mean. e. How far a particular score is from the median. 6. If the values in a data set are in feet, then what are the units for standard scores? a. Feet b. Square feet c. Square root of feet d. 1 Feet e. Standard scores do not have units. 2

3 Name: 7. Ramon is planning on buying a new car. He s looking at the Ford Escape a sport-utility vehicle which gets 28 highway miles per gallon, and the Ford Fusion a mid-sized sedan which gets 31 highway miles per gallon. The mean fuel efficiency for all sport utility vehicles is 23, with a standard deviation of 7.6. The mean of all mid-sized sedans is 27, with a standard deviation of 5.2. Which vehicle has a better standing, relative to others of the same style? a. The Ford Fusion sedan has a better relative standing, because it s z-score is higher b. The Ford Fusion sedan has a better relative standing., because it s z-score is closer to 0. c. The Ford Escape SUV has a better relative standing, because it s z-score is higher d. The Ford Escape SUV has a better relative standing, because it s z-score is closer to 0. e. We can t make any comparisons unless we know that the distribution of fuel efficiency for vehicle types is Normally distributed. Scenario 2-1 A sample was taken of the salaries of 20 employees of a large company. The following are the salaries (in thousands of dollars) for this year. For convenience, the data are ordered Suppose each employee in the company receives a $3,000 raise for next year (each employee's salary is increased by $3,000). 8. Use Scenario 2-1. The mean salary for the employees will a. be unchanged. b. increase by $3,000. c. be multiplied by $3,000. d. increase by $3,000. e. increase by $ Use Scenario 2-1. Use Scenario 2-1. The standard deviation of the salaries for the employees will a. be unchanged. b. increase by $3,000. c. be multiplied by $3,000. d. increase by $3,000. e. decrease by $3,000. 3

4 Name: 10. Which of the following dot plots would best be approximated by a Normal distribution? a. A d. D b. B e. E c. C 11. Birthweights at a local hospital have a Normal distribution with a mean of 110 oz. and a standard deviation of 15 oz. Which of the following is the proportion of infants with birthweights between 125 oz. and 140 oz.? a b c d e If the heights of 99.7% of American men are between 5' 0" and 7' 0", what is your estimate of the standard deviation of the height of American men? a. 1" b. 3" c. 4" d. 6" e. 12" 4

5 Name: 13. A company produces ceramic floor tiles that are supposed to have a surface area of 16.0 square inches. Due to variability in the manufacturing process, the actual surface area has a Normal distribution with a mean of 16.1 square inches and a standard deviation of 0.2 square inches. The proportion of tiles produced by the process with surface area less than 16.0 square inches is a b c d e The scores on a university examination are Normally distributed with a mean of 62 and a standard deviation of 11. If the bottom 5% of students will fail the course, what is the lowest mark that a student can have and still be awarded a passing grade? a. 40 b. 43 c. 44 d. 57 e A soft-drink machine can be regulated so that it discharges an average of µ oz. per cup. If the ounces of fill are Normally distributed with a standard deviation of 0.4 oz., what value should µ be set at so that 98% of 6-oz. cups will not overflow? a b c d e The time to complete a standardized exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given? a minutes b minutes c minutes d. 84 minutes e minutes 17. The five-number summary of the distribution of 316 scores on a statistics exam is The scores are approximately Normal. The standard deviation of test scores must be about a b c d. 10. e

6 Name: 18. A stemplot of a set of data is roughly symmetric, but the data do not even approximately follow the rule. We conclude that the data are a. Normal, but not Standard Normal. b. Standard Normal. c. not Normal. d. Normal. e. skewed in both directions. 19. Consider a distribution described by the density curve below: According to Chebyshev s inequality, the proportion of scores in this distribution that are within 3 standard deviations of the mean is at least a. 68% b. 75% c. 88% d. 95% e. Since this distribution is non-normal, Chebyshev s inequality does not apply. 20. Consider a distribution that is strongly skewed to the left. According to Chebyshev s inequality, the proportion of scores in this distribution that are within 2 standard deviations of the mean is at least a. 68% b. 75% c. 88% d. 95% e. Since this distribution is non-normal, Chebyshev s inequality does not apply. 6

7 Chapter 2 Review Answer Section MULTIPLE CHOICE 1. ANS: A PTS: 1 TOP: Density curve calculation 2. ANS: B PTS: 1 TOP: Percentiles 3. ANS: C PTS: 1 TOP: Percentiles 4. ANS: B PTS: 1 TOP: Cumulative relative freq. graph 5. ANS: D PTS: 1 TOP: Standard score idea 6. ANS: E PTS: 1 TOP: Standard score idea 7. ANS: A PTS: 1 TOP: compare relative standing 8. ANS: B PTS: 1 TOP: Impact of transformation on numerical summaries 9. ANS: A PTS: 1 TOP: Impact of transformation on numerical summaries 10. ANS: E PTS: 1 TOP: Recognizing Normal distribution 11. ANS: A PTS: 1 TOP: rule 12. ANS: C PTS: 1 TOP: rule 13. ANS: B PTS: 1 TOP: Normal Calculations 14. ANS: C PTS: 1 TOP: Normal Calculations 15. ANS: A PTS: 1 TOP: Inverse Normal Calculations 16. ANS: B PTS: 1 TOP: Inverse Normal Calculations 17. ANS: C PTS: 1 TOP: Standard deviation of Normal distribution from quartiles 18. ANS: C PTS: 1 TOP: and assessing normality 19. ANS: C PTS: 1 TOP: Chebyshev's inequality 20. ANS: B PTS: 1 TOP: Chebyshev's inequality 1