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About 77631 results. 1294 free access solutions
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| m6888 | A student needs to know details of a class assignment that is due the next day and decides to call fellow class members for this information. She believes that for any particular call, the probability of obtaining the necessary information is 0.40. She decides to continue calling class members until the information is obtained. But her cell phone battery will not allow more than 8 calls. Let the random variable X denote the number of calls needed to obtain the information.
a. Find the probability distribution of X.
b. Find the cumulative probability distribution of X.
c. Find the probability that at least three calls are required. |
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| m6889 | A study classified each of 134 lawyers into one of four groups based on observation and an interview. The 62 lawyers in group A were categorized as having high levels of stimulation and support and average levels of public spirit. The 52 lawyers in group B had low stimulation, average support, and high public spirit. Group C contained 7 lawyers with average stimulation, low support, and low public spirit. The 13 lawyers in group D were assessed as low on all three criteria. Salary levels for these four groups were compared. The sample means were 7.87 for group A, 7.47 for group B, 5.14 for group C, and 3.69 for group D. The F ratio calculated from these data was 25.60.
a. Prepare the complete analysis of variance table.
b. Test the null hypothesis that the population mean salaries are the same for lawyers in these four groups. |
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| m6890 | A study compared firms with and without an audit committee. For samples of firms of each type, the extent of directors ownership was measured using the number of shares owned by the board as a proportion of the total number of shares issued. In the sample, directors ownership was, overall, higher for firms without an audit committee. To test for statistical significance, the Mann-Whitney U statistic was calculated. It follows that (U - µU) /σU was found to be 2.12. What can we conclude from this result? |
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| m6891 | A study was aimed at assessing the class-schedule satisfaction levels, on a scale of 1 (very dissatisfied) to 7 (very satisfied), of nontenured faculty who were job-sharers, full time, or part-time. For a sample of 25 job-sharers, the mean satisfaction level was 6.60; for a sample of 24 full-time faculty the mean satisfaction level was 5.37; for a sample of 20 part-time faculty, the mean satisfaction level was 5.20. The F ratio calculated from these data was 6.62.
a. Prepare the complete analysis of variance table.
b. Test the null hypothesis of equality of the three population mean satisfaction levels. |
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| m6892 | A study was aimed at assessing the effects of group size and group characteristics on the generation of advertising concepts. To assess the influence of group size, groups of four and eight members were compared. For a random sample of four-member groups, the mean number of advertising concepts generated per group was 78.0 and the sample standard deviation was 24.4.
For an independent random sample of eight-member groups, the mean number of advertising concepts generated per group was 114.7 and the sample standard deviation was 14.6. (In each case, the groups had a moderator.) Stating any assumptions that you need to make, test, at the 1% level, the null hypothesis that the population means are the same against the alternative that the mean is higher for eight-member groups. |
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| m6893 | A study was conducted on the labor-hour costs of Federal Deposit Insurance Corporation (FDIC) audits of banks. Data were obtained on 91 such audits. Some of these were conducted by the FDIC alone and some jointly with state auditors. Auditors rated banks management as good, satisfactory, fair, or unsatisfactory. The model estimated was
where
y = FDIC auditor labor-hours
x1 = total assets of bank
x2 = total number of offices in bank
x3 = ratio of classified loans to total loans for bank
x4 = 1 if management rating was "good," 0 otherwise
x5 = 1 if management rating was "fair," 0 otherwise
x6 = 1 if management rating was "unsatisfactory," 0 otherwise
x7 = 1 if audit was conducted jointly with the state,
0 otherwise The numbers in parentheses beneath coefficient estimates are the associated standard errors. Write a report on these results. |
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| m6894 | A study was conducted to assess the influence of various factors on the start of new firms in the computer chip industry. For a sample of 70 countries the following model was estimated:
R2 = 0.766
where
y` = new business starts in the industry
x1 = population in millions
x2 = industry size
x3 = measure of economic quality of life
x4 = measure of political quality of life
x5 = measure of environmental quality of life
x6 = measure of health and educational quality of life
x7 = measure of social quality of life
The numbers in parentheses under the coefficients are the estimated coefficient standard errors.
a. Interpret the estimated regression coefficients.
b. Interpret the coefficient of determination.
c. Find a 90% confidence interval for the increase in new business starts resulting from a one-unit increase in the economic quality of life, with all other variables unchanged.
d. Test, against a two-sided alternative at the 5% level, the null hypothesis that, all else remaining equal, the environmental quality of life does not influence new business starts.
e. Test, against a two-sided alternative at the 5% level, the null hypothesis that, all else remaining equal, the health and educational quality of life does not influence new business starts.
f. Test the null hypothesis that, taken together, these seven independent variables do not influence new business starts. |
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| m6895 | A study was conducted to determine if there was a difference in humor content in British and American trade magazine advertisements. In an independent random sample of 270 American trade magazine advertisements, 56 were humorous. An independent random sample of 203 British trade magazine advertisements contained 52 humorous ads. Do these data provide evidence that there is a difference in the proportion of humorous ads in British versus American trade magazines?
Nutrition Research-Based Exercises
A large research study conducted by the Economic Research Service (ERS), a prestige think tank research center in the U.S. Department of Agriculture is conducting a series of research studies to determine the nutrition characteristics of people in the United States. This research is used for both nutrition education and government policy designed to improve personal health.
The U.S. Department of Agriculture (USDA) developed the Healthy Eating Index (HEI) to monitor the diet quality of the U.S. population, particularly how well it conforms to dietary guidance. The HEI-2005 measures how well the population follows the recommendations of the 2005 Dietary Guidelines for Americans. In particular, it measures, on a 100-point scale, the adequacy of consumption of vegetables, fruits, grains, milk, meat and beans, and liquid oils. Full credit for these groups is given only when the consumer consumes some whole fruit, vegetables from the dark green, orange, and legume subgroup, and whol |
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| m6896 | A study was conducted to determine whether certain features could be used to explain variability in the prices of furnaces. For a sample of 19 furnaces, the following regression was estimated:
y = price, in dollars
x1 = rating of furnace, in BTU per hour
x2 = energy efficiency ratio
x3 = number of settings
The numbers in parentheses under the coefficients are the estimated coefficient standard errors.
a. Find a 95% confidence interval for the expected increase in price resulting from an additional setting when the values of the rating and the energy efficiency ratio remain fixed.
b. Test the null hypothesis that, all else being equal, the energy efficiency ratio of furnaces does not affect their price against the alternative that the higher the energy efficiency ratio, the higher the price. |
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| m6897 | A supermarket developer has conducted a large study to determine alcohol preferences based on the type of vehicle typically driven to a shopping center. A random sample of 100 car drivers and a second random sample of 100 pickup truck drivers were interviewed and asked to indicate their preference for beer or wine. The results indicated that 68% of car drivers preferred wine, whereas 71% of pickup truck drivers preferred beer.
Construct a cross table and bar chart of this information. |
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| m6898 | A supervisor of a plant kept records of the time (in seconds) that employees needed to complete a particular task. The data are summarized as follows:
a. Graph the data with a histogram.
b. Discuss possible errors. |
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| m6899 | A survey carried out for a supermarket classified customers according to whether their visits to the store are frequent or infrequent and whether they often, sometimes, or never purchase generic products. The accompanying table gives the proportions of people surveyed in each of the six joint classifications.
a. What is the probability that a customer both is a frequent shopper and often purchases generic products?
b. What is the probability that a customer who never buys generic products visits the store frequently?
c. Are the events "never buys generic products" and "visits the store frequently" independent?
d. What is the probability that a customer who infrequently visits the store often buys generic products?
e. Are the events "often buys generic products" and "visits the store infrequently" independent?
f. What is the probability that a customer frequently visits the store?
g. What is the probability that a customer never buys generic products?
h. What is the probability that a customer either frequently visits the store or never buys generic products or both? |
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| m6900 | A survey research group conducts regular studies of households through mail questionnaires and is concerned about the factors influencing the response rate. In an experiment, 30 sets of questionnaires were mailed to potential respondents. The regression model fitted to the resulting data set was as follows:
Y = β0 + β1X1 + β2X2 + ε
where
Y = percentage of responses received
X1 = number of questions asked
X2 = length of questionnaire in number of words
Part of the SAS computer output from the estimate regression is shown next.
R@Square = 0.637
a. Interpret the estimated regression coefficients.
b. Interpret the coefficient of determination.
c. Test, at the 1% significance level, the null hypothesi that, taken together, the two independent variables do not linearly influence the response rate.
d. Find and interpret a 99% confidence interval for β1.
e. Test the null hypothesis
H0: β2 = 0
against the alternative
H0: β2 < 0
and interpret your findings. |
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| m6901 | A team of 5 analysts is about to examine the earnings prospects of 20 corporations. Each of the 5 analysts will study 4 of the corporations. These analysts are not equally competent. In fact, one of them is a star, having an excellent record of anticipating changing trends. Ideally, management would like to allocate the 4 corporations whose earnings will deviate most from past trends to this analyst. However, lacking this information, management allocates corporations to analysts randomly. What is the probability that at least 2 of the 4 corporations whose earnings will deviate most from past trends are allocated to the star analyst? |
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| m6902 | A team of marketing research students was asked to determine the pizza best liked by students enrolled in the team s college. Two years ago a similar study was conducted, and it was found that 40% of all students at this college preferred Bellini s pizza, 25% chose Anthony s pizza as the best, 20% selected Ferrara s pizza, and the rest selected Marie s pizza. To see if preferences have changed, 180 students were randomly selected and asked to indicate their pizza preferences. The results were as follows: 40 selected Ferrara s as their favorite, 32 students chose Marie s, 80 students preferred Bellini s, and the remainder selected Anthony s. Do the data indicate that the preferences today differ from those from the last study? |
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| m6903 | A team of undergraduate business students was asked to recommend improvement to the data entry process at the county appraiser s office. The team identified several types of errors, such as posting an incorrect name or entering an incorrect parcel number. The deed abstractors were asked to keep a record of the errors in data entry that were sent to them. The following table is a frequency distribution of errors:
Defect Total
Posting error in name ..................... 23
Posting error in parcel .................... 21
Property sold after tax bills were mailed .............. 5
Inappropriate call transfer (not part of deeds/mapping) ........ 18
Posting error in legal description>incomplete legal description .... 4
Deeds received after tax bills printed ............... 6
Correspondence errors .................... 2
Miscellaneous errors .................... 1
a. Construct a Pareto diagram of these defects in data entry.
b. What recommendations would you suggest to the county appraiser? |
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| m6904 | A test was taken by 90 students. A random sample of 10 scores found the following results:
93 71 62 75 81 63 87 59 84 72
a. Find a 90% confidence interval for the population’s mean score.
b. Without doing the calculations, state whether a 95% confidence interval for the population mean would be wider or narrower than the interval found in part a. |
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| m6905 | A textile manufacturer obtained a sample of 50 bolts of cloth from a day s output. Each bolt is carefully inspected and the number of imperfections is recorded as follows:
Find the mean, median, and mode for these sample data. |
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| m6906 | A time series contains 10 observations. What is the probability that the number of runs is
a. Fewer than 6?
b. No less than 4? |
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| m6907 | A time series contains 16 observations. What is the probability that the number of runs
a. Is at most 5?
b. Exceeds 12? |
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