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free/or 0.5$ |
| m264 | Bradford Electric Illuminating Company is studying the relationship between kilowatt-hours (thousands) used and the number of rooms in a private single-family residence. A random sample of 10 homes yielded the following.
a. Determine the regression equation.
b. Determine the number of kilowatt-hours, in thousands, for a six-roomhouse. |
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| m265 | Brooks Insurance Inc. wishes to offer life insurance to men age 60 via the Internet. Mortality tables indicate the likelihood of a 60-year-old man surviving another year is .98. If the policy is offered to five men age 60:
a. What is the probability all five men survive the year?
b. What is the probability at least one does not survive? |
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| m266 | Businesses, particularly those in the food preparation industry such as General Mills, Kellogg, and Betty Crocker, regularly use coupons as a brand allegiance builder to stimulate their retailing. There is uneasiness that the users of paper coupons are different from the users of e-coupons (coupons disseminated by means of the Internet). One survey recorded the age of each person who redeemed a coupon along with the type (either electronic or paper). The sample of 35 e-coupon users had a mean age of 33.6 years with a standard deviation of 10.9, while a similar sample of 25 traditional paper-coupon clippers had a mean age of 39.5 with a standard deviation of 4.8. Assume the population standard deviations are not the same. Using a significance level of .01, test the hypothesis of no difference in the mean ages of the two groups of coupon clients. |
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| m267 | Buster Posey of the San Francisco Giants had the highest batting average in the 2012 Major League Baseball season. His average was .336. So assume the probability of getting a hit is .336 for each time he batted. In a particular game, assume he batted three times.
a. This is an example of what type of probability?
b. What is the probability of getting three hits in a particular game?
c. What is the probability of not getting any hits in a game?
d. What is the probability of getting at least one hit? |
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| m268 | A byte is a sequence of eight bits and each bit is either 0 or 1.
(a) How many different bytes are possible?
(b) If the first bit of a byte is a parity check, that is, the first byte is determined from the other seven bits, how many different bytes are possible? |
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| m269 | Calculate a four-quarter weighted moving average for the number of shares outstanding for the Boxley Box Company for the nine quarters of data. The data are reported in thousands. Apply weights of .1, .2, .3, and .4, respectively, for the past three quarters and current quarter. In a few words, describe the trend in the number of subscribers.
1st Quarter 2011 ........... 28,766
2nd Quarter 2011 .......... 30,057
3rd Quarter 2011 .......... 31,336
4th Quarter 2011 .......... 33,240
1st Quarter 2012 .......... 34,610
2nd Quarter 2012 ........... 35,102
3rd Quarter 2012 .......... 35,308
4th Quarter 2012 .......... 35,203
1st Quarter 2013 .......... 34,386 |
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| m270 | Calorie Watchers has low-calorie breakfasts, lunches, and dinners. If you join the club, you receive two packaged meals a day. Calorie Watchers claims that you can eat anything you want for the third meal and still lose at least 5 pounds the first month. Members of the club are weighed before commencing the program and again at the end of the first month. The experiences of a random sample of 11 enrollees are:
.:.
We are interested in whether there has been a weight loss as a result of the Calorie Watchers program.
a. State H0 and H 1.
b. Using the .05 level of significance, what is the decision rule?
c. What is your conclusion about the Calorie Watchers program? |
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| m271 | Cellulon, a manufacturer of home insulation, wants to develop guidelines for builders and consumers on how the thickness of the insulation in the attic of a home and the outdoor temperature affect natural gas consumption. In the laboratory, it varied the insulation thickness and temperature. A few of the findings are:
On the basis of the sample results, the regression equation is:
yˆ = 62.65 – 1.86x1 – 0.52x2
a. How much natural gas can homeowners expect to use per month if they install 6 inches of insulation and the outdoor temperature is 40 degrees F?
b. What effect would installing 7 inches of insulation instead of 6 have on the monthly natural gas consumption (assuming the outdoor temperature remains at 40 degrees F)?
c. Why are the regression coefficients b1 and b2 negative? Is thislogical? |
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| m272 | Central Airlines claims that the median price of a round-trip ticket from Chicago to Jackson Hole, Wyoming, is $503. This claim is being challenged by the Association of Travel Agents, who believe the median price is less than $503. A random sample of 400 round-trip tickets from Chicago to Jackson Hole revealed 160 tickets were below $503. None of the tickets was exactly $503. Let α = .05.
a. State the null and alternate hypotheses.
b. What is your decision regarding H0? Interpret. |
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| m273 | Chapin Manufacturing Company operates 24 hours a day, 5 days a week. The workers rotate shifts each week. Management is interested in whether there is a difference in the number of units produced when the employees work on various shifts. A sample of five workers is selected and their output recorded on each shift. At the .05 significance level, can we conclude there is a difference in the mean production rate by shift or byemployee? |
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| m274 | Charter National Bank has a staff of loan officers located in its branch offices throughout the Southwest. Robert Kerns, vice president of consumer lending, would like some information on the typical amount of loans and the range in the amount of the loans. A staff analyst of the vice president selected a sample of 10 loan officers and from each officer selected a sample of five loans he or she made last month. The data are reported below. Develop a control chart for the mean and the range. Do any of the officers appear to be “out of control”? Comment on yourfindings. |
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| m275 | Chicken Delight claims that 90% of its orders are delivered within 10 minutes of the time the order is placed. A sample of 100 orders revealed that 82 were delivered within the promised time. At the .10 significance level, can we conclude that less than 90% of the orders are delivered in less than 10 minutes? |
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| m276 | Christina Sanders is a member of the women’s basketball team at Windy City College. Last season, she made 55% of her free throw attempts. In an effort to improve this statistic, she attended a summer camp devoted to foul-shooting techniques. The next 20 days she shot 100 foul shots a day. She carefully recorded the number of attempts made each day. The results are reported below.
To interpret, the first day she made 55 out of 100, or 55%. The last day she made 67 out of 100, or 67%.
a. Develop a control chart for the proportion of shots made. Over the 20 days of practice, what percent of attempts did she make? What are the upper and lower control limits for the proportion of shots made?
b. Is there any trend in her proportion made? Does she seem to be improving, staying the same, or getting worse?
c. Find the percent of attempts made for the last 5 days of practice. Use the hypothesis testing procedure, formula (10–4), to determine if there is an improvement from55%. |
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| m277 | Cincinnati Paint Company sells quality brands of paints through hardware stores throughout the United States. The company maintains a large sales force whose job it is to call on existing customers as well as look for new business. The national sales manager is investigating the relationship between the number of sales calls made and the miles driven by the sales representative. Also, do the sales representatives who drive the most miles and make the most calls necessarily earn the most in sales commissions? To investigate, the vice president of sales selected a sample of 25 sales representatives and determined:
• The amount earned in commissions last month ( y)
• The number of miles driven last month (x1)
• The number of sales calls made last month (x2)
The information is reported below.
Develop a regression equation including an interaction term. Is there a significant interaction between the number of sales calls and the milesdriven? |
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| m278 | City planners believe that larger cities are populated by older residents. To investigate the relationship, data on population and median age in 10 large cities were collected.
a. Plot these data on a scatter diagram with median age as the dependent variable.
b. Find the correlation coefficient.
c. A regression analysis was performed and the resulting regression equation is Median Age 5 31.4 1 0.272 Population. Interpret the meaning of the slope.
d. Estimate the median age for a city of 2.5 million people.
e. Here is a portion of the regression software output. What does it tell you?
f. Using the .10 significance level, test the significance of the slope. Interpret the result. Is there a significant relationship between the twovariables? |
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| m279 | Clark Heter is an industrial engineer at Lyons Products. He would like to determine whether there are more units produced on the night shift than on the day shift. Assume the population standard deviation for the number of units produced on the day shift is 21 and is 28 on the night shift. A sample of 54 day-shift workers showed that the mean number of units produced was 345. A sample of 60 night-shift workers showed that the mean number of units produced was 351. At the .05 significance level, is the number of units produced on the night shift larger? |
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| m280 | Classic Golf Inc. manages five courses in the Jacksonville, Florida, area. The director of golf wishes to study the number of rounds of golf played per weekday at the five courses. He gathered the following sample information. At the .05 significance level, is there a difference in the number of rounds played by day of the week?
Day Rounds
Monday ......... 124
Tuesday ......... 74
Wednesday ......... 104
Thursday .......... 98
Friday ........... 120 |
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| m281 | Commercial Bank and Trust Company is studying the use of its automatic teller machines (ATMs). Of particular interest is whether young adults (under 25 years) use the machines more than senior citizens. To investigate further, samples of customers under 25 years of age and customers over 60 years of age were selected. The number of ATM transactions last month was determined for each selected individual, and the results are shown below. At the .01 significance level, can bank management conclude that younger customers use the ATMsmore? |
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| m282 | A company employs 800 men under the age of 55. Suppose that 30% carry a marker on the male chromosome that indicates an increased risk for high blood pressure.
(a) If 10 men in the company are tested for the marker in this chromosome, what is the probability that exactly 1 man has the marker?
(b) If 10 men in the company are tested for the marker in this chromosome, what is the probability that more than 1 has the marker? |
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| m283 | A company performs inspection on shipments from suppliers in order to defect nonconforming products. Assume a lot contains 1000 items and 1% are nonconforming. What sample size is needed so that the probability of choosing at least one nonconforming item in the sample is at least 0.90? Assume the binomial approximation to the hypergeometric distribution is adequate. |
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