232Sample TEST BANK - INTRODUCTION TO THE PRACTICE OF...

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INTRODUCTION TO THE PRACTICE OF STATISTICS FIFTH EDITION INSTRUCTOR RESOURCES SAMPLE TEST BANK CHAPTER 1 SAMPLE TEST BANK QUESTIONS A sample was taken of the salaries of four employees from a large company. The following are their salaries (in thousands of dollars) for this year. 33 31 24 36 The variance of their salaries is a. 5.1. b. 26. c. 31. A teacher gave a 25 question multiple choice test. After scoring the tests, she computed a mean and standard deviation of the scores. The standard deviation was 0. Based on this information a. All the students had the same score. b. She must have made a mistake. c. About half the scores were above the mean. A sample of 160 workers in the downtown area classified each worker by race. A bar graph of the results is given below, but the bar for blacks in the graph below has been omitted. Using the information provided, the proportion of black workers in the sample must be a. 40%. b. 25%. c. 20%. You receive a fax with six bids (in millions of dollars) 2.2, 1.3, 1.9, 1.2, 2.4, and x , where x is some number that is too blurry to read. Without knowing what x is, the median a. is 1.9. b. must be between 1.3 and 2.2. c. could be any number between 1.2 and 2.4.
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For a physics course containing 10 students, the maximum point total for the quarter was 200. The point totals for the 10 students are given in the stem plot below. a. Since there are 7 stems, the median must be con-tained in the fourth smallest stem and be between 140 and 150. b. We can compute the mean number of points for the 10 students from the information in the stem plot. c. Because of the small sample size, it would be impossible to split the stems in this stem plot. Consider the following stemplot. The mean of the data represented in this stemplot a. is 34.5. b. is 37. c. cannot be computed from the information given. An eager statistics student wanted to help his boss. He studied the data on products sold at the store over a period of a week and reported to the boss the average UPC number was 1001264789 with a standard deviation of 45378. From this information his boss should a. Make sure there are lots of 1001264789 items on hand. b. Know that approximately 68% of all items had UPC codes between 1001219411 and 1001310167. c. Do nothing with the information. The statistics reported are invalid. Does the value of the standard deviation depend on the value of the mean? a. Yes. If the mean gets larger the standard deviation will also get larger. b. Yes. You need to know the mean to be able to calculate the standard deviation. c. No. The center of a distribution and the spread are not related.
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The lifetime of a 2-volt non-rechargeable battery in constant use has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. The proportion of batteries with lifetimes exceeding 520 hours is approximately a. 0.2000. b. 0.5793. c. 0.4207.
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