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free/or 0.5$ |
| m123 | A senior accounting major at Midsouth State University has job offers from four CPA firms. To explore the offers further, she asked a sample of recent trainees how many months each worked for the firm before receiving a raise in salary. The sample information is submitted to Minitab with the following results:
At the .05 level of significance, is there a difference in the mean number of months before a raise was granted among the four CPAfirms? |
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| m124 | A series of questions on sports and world events was asked of 14 randomly selected young adult naturalized citizens. The results were translated into sports and world events “knowledge” scores. The scores were:
a. Determine the degree of association between how the citizens ranked with respect to knowledge of sports and how they ranked on world events.
b. At the .05 significance level, is the rank correlation between the sports and world events “knowledge” scores greater thanzero? |
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| m125 | A six-sided die is rolled 30 times and the numbers 1 through 6 appear as shown in the following frequency distribution. At the .10 significance level, can we conclude that the die isfair? |
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| m126 | A small business consultant is investigating the performance of several companies. The
Fourth quarter sales for last year (in thousands of dollars) for the selected companies were:
Fourth-Quarter Sales
Company ($ thousands)
Hoden Building Products .......... $ 1,645.2
J & R Printing Inc. ............ 4,757.0
Long Bay Concrete Construction...... 8,913.0
Mancell Electric and Plumbing......... 627.1
Maxwell Heating and Air Conditioning.... 24,612.0
Mizelle Roofing & Sheet Metals........ 191.9
The consultant wants to include a chart in his report comparing the sales of the six companies. Use a bar chart to compare the fourth-quarter sales of these corporations and write a brief report summarizing the bar chart. |
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| m127 | A social scientist is studying the use of iPods by college students. A sample of 45 students revealed they played the following number of songs yesterday.
Organize the above information into a frequency distribution.
a. How many classes would you suggest?
b. What is the most suitable class interval?
c. What is the lower limit of the initial class?
d. Create the frequency distribution.
e. Describe the profile of thedistribution. |
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| m128 | A sociologist claims that the success of students in college (measured by their GPA) is related to their family’s income. For a sample of 20 students, the correlation coefficient is 0.40. Using the 0.01 significance level, can we conclude that there is a positive correlation between the variables? |
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| m129 | A software design company is creating a new, faster search engine. The search engine is clearly faster, but initial tests indicate there is more variation in the time to perform a search. A sample of 16 different searches showed that the standard deviation of the search time was 22 hundredths of a second for the new search engine and 12 hundredths of a second for the current search engine. At the .05 significance level, can we conclude that there is more variation in the search time of the new search engine? |
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| m130 | A special-purpose index is to be designed to monitor the overall economy of the Southwest. Four key series were selected. After considerable deliberation, it was decided to weight retail sales 20%, total bank deposits 10%, industrial production in the area 40%, and nonagricultural employment 30%. The data for 1996 and 2013 are:
Construct a special-purpose index for 2013 using 1996 as the base period andinterpret. |
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| m131 | A statewide real estate sales agency, Farm Associates, specializes in selling farm property in the state of Nebraska. Its records indicate that the mean selling time of farm property is 90 days. Because of recent drought conditions, the agency believes that the mean selling time is now greater than 90 days. A statewide survey of 100 farms sold recently revealed that the mean selling time was 94 days, with a standard deviation of 22 days. At the .10 significance level, has there been an increase in selling time? |
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| m132 | A stock analyst wants to determine whether there is a difference in the mean rate of return for three types of stock: utility, retail, and banking stocks. The following output is obtained:
a. Using the .05 level of significance, is there a difference in the mean rate of return among the three types of stock?
b. Can the analyst conclude there is a difference between the mean rates of return for utility and retail stocks? For utility and banking stocks? For banking and retail stocks?Explain. |
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| m133 | A stockbroker at Critical Securities reported that the mean rate of return on a sample of 10 oil stocks was 12.6% with a standard deviation of 3.9%. The mean rate of return on a sample of 8 utility stocks was 10.9% with a standard deviation of 3.5%. At the .05 significance level, can we conclude that there is more variation in the oil stocks? |
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| m134 | A student is taking two courses, history and math. The probability the student will pass the history course is .60, and the probability of passing the math course is .70. The probability of passing both is .50. What is the probability of passing at least one? |
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| m135 | A study conducted by the nationally known Taurus Health Club revealed that 30% of its new members are 15 pounds overweight. A membership drive in a metropolitan area resulted in 500 new members.
a. It has been suggested that the normal approximation to the binomial be used to determine the probability that 175 or more of the new members are 15 pounds overweight. Does this problem qualify as a binomial problem? Explain.
b. What is the probability that 175 or more of the new members are 15 pounds overweight?
c. What is the probability that 140 or more new members are 15 pounds overweight? |
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| m136 | A study is made by the recording industry in the United States of the number of music CDs owned by 25 senior citizens and 30 young adults. The information is reported below.
a. Find the median and the first and third quartiles for the number of CDs owned by senior citizens. Develop a box plot for the information.
b. Find the median and the first and third quartiles for the number of CDs owned by young adults. Develop a box plot for the information.
c. Compare the number of CDs owned by the twogroups. |
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| m137 | A study of 20 worldwide financial institutions showed the correlation between their assets and pretax profit to be .86. At the .05 significance level, can we conclude that there is positive correlation in the population? |
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| m138 | A study of 200 advertising firms revealed their income after taxes:
Income after Taxes Number of Firms
Under $1 million ......... 102
$1 million to $20 million....... 61
$20 million or more......... 37
a. What is the probability an advertising firm selected at random has under $1 million in income after taxes?
b. What is the probability an advertising firm selected at random has either an income between $1 million and $20 million, or an income of $20 million or more? What rule of probability was applied? |
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| m139 | A study of long-distance phone calls made from General Electric Corporate Headquarters in Fairfield, Connecticut, revealed the length of the calls, in minutes, follows the normal probability distribution. The mean length of time per call was 4.2 minutes and the standard deviation was 0.60 minute.
a. What fraction of the calls lasts between 4.2 and 5 minutes?
b. What fraction of the calls lasts more than 5 minutes?
c. What fraction of the calls lasts between 5 and 6 minutes?
d. What fraction of the calls lasts between 4 and 6 minutes?
e. As part of her report to the president, the director of communications would like to report the length of the longest (in duration) 4% of the calls. What is this time? |
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| m140 | A study of the attendance at the University of Alabama’s basketball games revealed that the distribution of attendance is normally distributed with a mean of 10,000 and a standard deviation of 2,000.
a. What is the probability a particular game has an attendance of 13,500 or more?
b. What percent of the games have an attendance between 8,000 and 11,500?
c. Ten percent of the games have an attendance of how many or less? |
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| m141 | A study of the checkout lines at the Safeway Supermarket in the South Strand area revealed that between 4 and 7 p.m. on weekdays there is an average of four customers waiting in line. What is the probability that you visit Safeway today during this period and find:
a. No customers are waiting?
b. Four customers are waiting?
c. Four or fewer are waiting?
d. Four or more are waiting? |
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| m142 | A study of the effect of television commercials on 12-year-old children measured their attention span, in seconds. The commercials were for clothes, food, and toys. At the .05 significance level, is there a difference in the mean attention span of the children for the various commercials? Are there significant differences between pairs of means? Would you recommend dropping one of the three commercialtypes? |
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