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Quiz 1 SP 05 KEY

# Quiz 1 SP 05 KEY - An office manager took a sample of the...

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Name KEY SSN ECON 2843 Spring 2005 Quiz 1 Students must show all work on problems that involve calculation, even if the question is multiple choice. Questions 1 through 4 refer to the following: A computer corporation wanted to know information about the age distribution of the customers who use its computers. The results of the population of last month’s new customers were as follows. Cumulative Age of relative Primary User frequency 3 – 11 .08 12 – 20 .38 21 – 29 .58 30 – 38 .73 39 – 47 .85 48 – 56 .95 57 – 65 1 1. What is the mean age for this population? a. 3.5 b. 28.87 * c. 34 d. 35.27 e. impossible to determine based on the given information 2. What is the standard deviation?

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3. If one of the individuals is selected randomly, what is the probability that the user will be older than the median class ? 4. What is the modal class ? Questions 5 – 9 refer to the following.
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Unformatted text preview: An office manager took a sample of the number of cups of coffee that employees in the office drank at work in one month. The results of the sample are as follows: 30 , 12 , 0 , 15 , 26 , 40 , 10 , 12 5. Using the correct symbol, calculate the variance. a. 12.05 b. 12.88 c. 145.11 d. 158 e. 165.84 * 6. What is the interquartile range? a. 4.5 b. 18 c. 20 * d. 35.5 e. 40 7. Calculate the coefficient of variation. 2 2 a. .6 b. .7 c. 66.46% d. 71.05% * e. 95% 8. What is the range? a. 3.5 b. 18 c. 19 d. 40 * e. 52 9. What is the median? a. .25 b. 13.5 * c. 20.5 d. 26 e. 30 10.A manufacturer claims that the lightbulbs he produces have a mean lifetime of 1,400 hours and that the standard deviation of lifetimes is 150 hours. Find a range in which it can be guaranteed that at least 8/9ths (or about 88.9%) of the lifetimes of these bulbs lie. (950 , 1,850)...
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