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free/or 0.5$ |
| m86 | A recent article reported that a job awaits only one in three new college graduates. The major reasons given were an overabundance of college graduates and a weak economy. A survey of 200 recent graduates from your school revealed that 80 students had jobs. At the .01 significance level, can we conclude that a larger proportion of students at your school have jobs? |
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| m87 | A recent CBS News survey reported that 67% of adults felt the U.S. Treasury should continue making pennies.
Suppose we select a sample of 15 adults.
a. How many of the 15 would we expect to indicate that the Treasury should continue making pennies? What is the standard deviation?
b. What is the likelihood that exactly eight adults would indicate the Treasury should continue making pennies?
c. What is the likelihood at least eight adults would indicate the Treasury should continue makingpennies? |
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| m88 | A recent issue of Bride Magazine suggested that couples planning their wedding should expect two-thirds of those who are sent an invitation to respond that they will attend. Rich and Stacy are planning to be married later this year. They plan to send 197 invitations.
a. How many guests would you expect to accept the invitation?
b. What is the standard deviation?
c. What is the probability 140 or more will accept the invitation?
d. What is the probability exactly 140 will accept the invitation? |
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| m89 | A recent national survey found that high school students watched an average (mean) of 6.8 DVDs per month with a population standard deviation of 1.8. The distribution of DVDs watched per month follows the normal distribution. A random sample of 36 college students revealed that the mean number of DVDs watched last month was 6.2. At the .05 significance level, can we conclude that college students watch fewer DVDs a month than high school students?
(a) State the null hypothesis and the alternate hypothesis.
(b) State the decision rule.
(c) Compute the value of the test statistic.
(d) What is your decision regarding H0?
(e) What is the p-value? Interpret it. |
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| m90 | A recent news report indicated that 20% of all employees steal from their company each year. If a company employs 50 people, what is the probability that:
a. Fewer than five employees steal?
b. More than five employees steal?
c. Exactly five employees steal?
d. More than 5 but fewer than 15 employees steal? |
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| m91 | A recent report indicated a typical family of four spends $490 per month on food. Assume the distribution of food expenditures for a family of four follows the normal distribution, with a standard deviation of $90 per month.
a. What percent of the families spend more than $30 but less than $490 per month on food?
b. What percent of the families spend less than $430 per month on food?
c. What percent spend between $430 and $600 per month on food?
d. What percent spend between $500 and $600 per month on food? |
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| m92 | A recent study by the Greater Los Angeles Taxi Drivers Association showed that the mean fare charged for service from Hermosa Beach to Los Angeles International Airport is $21 and the standard deviation is $3.50. We select a sample of 15 fares.
a. What is the likelihood that the sample mean is between $20 and $23?
b. What must you assume to make the above calculation? |
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| m93 | A recent study compared the time spent together by single- and dual-earner couples. Ac-cording to the records kept by the wives during the study, the mean amount of time spent together watching television among the single-earner couples was 61 minutes per day, with a standard deviation of 15.5 minutes. For the dual-earner couples, the mean number of minutes spent watching television was 48.4 minutes, with a standard deviation of 18.1 minutes. At the .01 significance level, can we conclude that the single-earner couples on average spend more time watching television together? There were 15 single-earner and 12 dual-earner couples studied. |
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| m94 | A recent study conducted by Penn, Shone, and Borland, on behalf of LastMinute.com, revealed that 52% of business travelers plan their trips less than two weeks before departure. The study is to be replicated in the tri-state area with a sample of 12 frequent business travelers.
a. Develop a probability distribution for the number of travelers who plan their trips within two weeks of departure.
b. Find the mean and the standard deviation of this distribution.
c. What is the probability exactly 5 of the 12 selected business travelers plan their trips within two weeks of departure?
d. What is the probability 5 or fewer of the 12 selected business travelers plan their trips within two weeks of departure? |
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| m95 | A recent study focused on the number of times men and women who live alone buy take-out dinner in a month. Assume that the distributions follow the normal probability distribution and the population standard deviations are equal. The information is summarized below.
At the .01 significance level, is there a difference in the mean number of times men and women order take-out dinners in a month? What is thep-value? |
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| m96 | A recent study of home technologies reported the number of hours of personal computer usage per week for a sample of 60 persons. Excluded from the study were people who worked out of their home and used the computer as a part of their work.
a. Organize the data into a frequency distribution. How many classes would you suggest?
What value would you suggest for a class interval?
b. Draw a histogram. Interpret yourresult. |
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| m97 | A recent study of the hourly wages of maintenance crew members for major airlines showed that the mean hourly salary was $20.50, with a standard deviation of $3.50. Assume the distribution of hourly wages follows the normal probability distribution. If we select a crew member at random, what is the probability the crew member earns:
a. Between $20.50 and $24.00 per hour?
b. More than $24.00 per hour?
c. Less than $19.00 per hour? |
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| m98 | A recent study revealed the typical American coffee drinker consumes an average of 3.1 cups per day. A sample of 12 senior citizens revealed they consumed the following amounts of coffee, reported in cups, yesterday.
At the .05 significance level, do these sample data suggest there is a difference between the national average and the sample mean from seniorcitizens? |
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| m99 | A recent survey by the American Accounting Association revealed 23% of students graduating with a major in accounting select public accounting. Suppose we select a sample of 15 recent graduates.
a. What is the probability two select public accounting?
b. What is the probability five select public accounting?
c. How many graduates would you expect to select public accounting? |
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| m100 | A recent survey compared the costs of adoption through public and private agencies. For a sample of 16 adoptions through a public agency, the mean cost was $21,045, with a standard deviation of $835. For a sample of 18 adoptions through a private agency, the mean cost was $22,840, with a standard deviation of $1,545. Can we conclude the mean cost is larger for adopting children through a private agency? Use the .05 significance level. |
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| m101 | A recent survey reported in Bloomberg Business week dealt with the salaries of CEOs at large corporations and whether company shareholders made money or lost money.
If a company is randomly selected from the list of 20 studied, what is the probability:
a. The CEO made more than $1 million?
b. The CEO made more than $1 million or the shareholders lost money?
c. The CEO made more than $1 million given the shareholders lost money?
d. Of selecting two CEOs and finding they both made more than $1million? |
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| m102 | A recent survey showed that the typical American car owner spends $2,950 per year on operating expenses. Below is a breakdown of the various expenditure items. Draw an appropriate chart to portray the data and summarize your findings in a brief report.
Expenditure Item Amount
Fuel ............. $ 603
Interest on car loan...... 279
Repairs ........... 930
Insurance and license...... 646
Depreciation ......... 492
Total ............. $2,950 |
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| m103 | A regional commuter airline selected a random sample of 25 flights and found that the correlation between the number of passengers and the total weight, in pounds, of luggage stored in the luggage compartment is 0.94. Using the .05 significance level, can we conclude that there is a positive association between the two variables? |
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| m104 | A regional planner is studying the demographics in a region of a particular state. She has gathered the following data on nine counties.
a. Is there a linear relationship between the median income and median age?
b. Which variable is the “dependent” variable?
c. Use statistical software to determine the regression equation. Interpret the value of the slope in a simple regression equation.
d. Include the aspect that the county is “coastal” or not in a multiple linear regression analysis using a “dummy” variable. Does it appear to be a significant influence on incomes?
e. Test each of the individual coefficients to see if they are significant.
f. Make a plot of the residuals and comment on whether they appear to follow a normal distribution.
g. Plot the residuals versus the fitted values. Do they seem to have the same amount ofvariation? |
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| m105 | A regression analysis relating the current market value in dollars to the size in square feet of homes in Greene County, Tennessee, follows. The regression equation is: Value 5 237,186 1 65.0 Size.
a. How many homes were in the sample?
b. Compute the standard error of estimate.
c. Compute the coefficient of determination.
d. Compute the correlation coefficient.
e. At the .05 significance level, does the evidence suggest a positive association between the market value of homes and the size of the home in squarefeet? |
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