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About 77631 results. 1294 free access solutions
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| m6908 | A time series contains 50 observations. What is the probability that the number of runs is
a. no more than 14?
b. fewer than 16?
c. greater than 28? |
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| m6909 | A town has 500 real estate agents. The mean value of the properties sold in a year by these agents is $800,000, and the standard deviation is $300,000. A random sample of 100 agents is selected, and the value of the properties they sold in a year is recorded.
a. What is the standard error of the sample mean?
b. What is the probability that the sample mean exceeds $825,000?
c. What is the probability that the sample mean exceeds $780,000?
d. What is the probability that the sample mean is between $790,000 and $820,000? |
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| m6910 | A traditional test for extra- sensory perception (ESP) involves a set of playing cards, each of which shows a different symbol (circle, square, cross, star, or wavy lines). If C represents a correct guess and I an incorrect guess, what is the probability of
(a) C?
(b) CI (in that order) for two guesses?
(c) CCC for three guesses?
(d) III for three guesses? |
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| m6911 | A travel agent randomly sampled individuals in her target market and asked, Did you use a travel agent to book your last airline flight? By cross-referencing the answers to this question with the responses to the rest of the questionnaire, the agent obtained data such as that in the following contingency table:
Determine if there is an association between the respondent s age and use of a travel agent to make reservations for the respondent s last flight. |
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| m6912 | A union executive wants to estimate the mean value of bonus payments made to a corporation s clerical employees in the first month of a new plan. This corporation has 52 subdivisions, and a simple random sample of 8 of these is taken. Information is then obtained from the payroll records of every clerical worker in each of the sampled subdivisions. The results obtained are shown in the following table:
a. Find a point estimate of the population mean bonus per clerical employee for this month.
b. Find a 99% confidence interval for the population mean. |
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| m6913 | A university administrator requested a breakdown of travel expenses for faculty to attend various professional meetings. It was found that 31% of the travel expenses was spent for transportation costs, 25% was spent for lodging, 17% was spent for food, and 20% was spent for conference registration fees; the remainder was spent for miscellaneous costs.
a. Construct a pie chart.
b. Construct a bar chart. |
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| m6914 | A university research team was studying the relationship between idea generation by groups with and without a moderator. For a random sample of four groups with a moderator, the mean number of ideas generated per group was 78.0, and the standard deviation was 24.4. For a random sample of four groups without a moderator, the mean number of ideas generated was 63.5, and the standard deviation was 20.2. Test the assumption that the two population variances were equal against the alternative that the population variance is higher for groups with a moderator. |
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| m6915 | A video movie store owner finds that 30% of the customers entering the store ask an assistant for help and that 20% of the customers make a purchase before leaving. It is also found that 15% of all customers both ask for assistance and make a purchase. What is the probability that a customer does at least one of these two things? |
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| m6916 | A video-rental chain estimates that annual expenditures of members on rentals follow a normal distribution with a mean of $100. It was also found that 10% of all members spend more than $130 in a year. What percentage of members spends more than $140 in a year? |
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| m6917 | A wine producer claims that the proportion of its customers who cannot distinguish its product from frozen grape juice is, at most, 0.09. The producer decides to test this null hypothesis against the alternative that the true proportion is more than 0.09. The decision rule adopted is to reject the null hypothesis if the sample proportion of people who cannot distinguish between these two flavors exceeds 0.14.
a. If a random sample of 100 customers is chosen, what is the probability of a Type I error, using this decision rule?
b. If a random sample of 400 customers is selected, what is the probability of a Type I error, using this decision rule? Explain, in words and graphically, why your answer differs from that in part a.
c. Suppose that the true proportion of customers who cannot distinguish between these flavors is 0.20. If a random sample of 100 customers is selected, what is the probability of a Type II error?
d. Suppose that, instead of the given decision rule, it is decided to reject the null hypothesis if the sample proportion of customers who cannot distinguish between the two flavors exceeds 0.16. A random sample of 100 customers is selected.
i. Without doing the calculations, state whether the probability of a Type I error will be higher than, lower than, or the same as in part a.
ii. If the true proportion is 0.20, will the probability of a Type II error be higher than, lower than, or
the same as in part c? |
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| m6918 | A work crew for a building project is to be made up of 2 craftsmen and 4 laborers selected from a total of 5 craftsmen and 6 laborers.
a. How many different combinations are possible?
b. The brother of one of the craftsmen is a laborer. If the crew is selected at random, what is the probability that both brothers will be selected?
c. What is the probability that neither brother will be selected? |
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| m6919 | Abdul Hassan, president of Floor Coverings Unlimited, has asked you to study the relationship between market price and the tons of rugs supplied by his competitor, Best Floor, Inc. He supplies you with the following observations of price per ton and number of tons, obtained from his secret files:
12, 5214, 10213, 8216, 18213, 6215, 15216, 20212, 42
The first number for each observation is price and the second is quantity.
a. Prepare a scatter plot.
b. Determine the regression coefficients, b0 and b1.
c. Write a short explanation of the regression equation that tells Abdul how the equation can be used to describe his competition. Include an indication of the range over which the equation can be applied. |
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| m6920 | According to a 2009 survey based on the United States Census (http://www.census.gov/prod/(http://www.census.gov/prod/2011pubs/acs-15.pdf), (http://www.census.gov/prod/2011pubs/acs-15.pdf), the daily one- way commute time of U. S. workers averages 25 minutes with ( we’ll assume) a standard deviation of 13 minutes. An investigator wishes to determine whether the national average describes the mean commute time for all workers in the Chicago area. Commute times are obtained for a random sample of 169 workers from this area, and the mean time is found to be 22.5 minutes. Test the null hypothesis at the .05 level of significance. |
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| m6921 | According to the California Educational Code (http://www.cde.ca.gov/ (http://www.cde.ca.gov/ls/fa/sf/peguidemidhi.asp), ls/fa/sf/peguidemidhi.asp), students in grades 7– 12 should receive 400 minutes of physical education every 10 school days. A random sample of 48 students has a mean of 385 minutes and a standard deviation of 53 minutes. Test the hypothesis at the .05 level of significance that the sampled population satisfies the requirement. |
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| m6922 | According to the Internal Revenue Service, 75% of all tax returns lead to a refund. A random sample of 100 tax returns is taken.
a. What is the mean of the distribution of the sample proportion of returns leading to refunds?
b. What is the variance of the sample proportion?
c. What is the standard error of the sample proportion?
d. What is the probability that the sample proportion exceeds 0.8? |
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| m6923 | Acme Delivery offers three different shipping rates for packages fewer than 5 pounds delivered from Maine to the West Coast: regular, $3; fast, $5; and lightning, $10. To test the quality of these services, a major mailorder retailer shipped 15 packages at randomly selected times from Maine to Tacoma, Washington. The packages were shipped in groups of three by the three services at the same time to reduce variation resulting from the shipping day. The following data show the shipping cost, X, and the number of days, Y, in (x, y) pairs:
13, 72 15, 52 110, 22 13, 92 15, 62 110, 52 13, 62 15, 62 110, 12 13, 102 15, 72 110, 42 13, 52 15, 62 110, 42
a. Describe the data numerically (covariance and correlation).
b. Discuss the value of the higher-priced services in terms of quicker delivery. |
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| m6924 | Acme Delivery offers three different shipping rates for packages under 5 pounds delivered from Maine to the West Coast: regular, $3; fast, $5; and lightning, $10. To test the quality of these services, a major mail-order retailer shipped 15 packages at randomly selected times from Maine to Tacoma, Washington.
The packages were shipped in groups of three by the three services at the same time to reduce variation resulting from the shipping day. The following data show the shipping cost, X, and the number of days, Y, in (x, y) pairs:
13, 72 15, 52 110, 22 13, 92 15, 62 110, 52 13, 62 15, 62 110, 12 13, 102 15, 72 110, 42 13, 52 15, 62 110, 42
Prepare a scatter plot of the points and comment on the relationship between shipping cost and observed delivery time. |
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| m6925 | Add 10 to each of the scores in Question 4.4 (1, 3, 4, 4) to produce a new distribution (11, 13, 14, 14). Would you expect the value of the sample standard deviation to be the same for both the original and new distributions? Explain your answer, and then calculate s for the new distribution. |
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| m6926 | Add 10 to only the smallest score in Question 4.4 (1, 3, 4, 4) to produce another new distribution (11, 3, 4, 4). Would you expect the value of s to be the same for both the original and new distributions? Explain your answer, and then calculate s for the new distribution. |
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| m6927 | Admission to a state university depends partially on the applicant’s high school GPA. Assume that the applicants’ GPAs approximate a normal curve with a mean of 3.20 and a standard deviation of 0.30.
(a) If applicants with GPAs of 3.50 or above are automatically admitted, what proportion of applicants will be in this category?
(b) If applicants with GPAs of 2.50 or below are automatically denied admission, what proportion of applicants will be in this category?
(c) A special honors program is open to all applicants with GPAs of 3.75 or better. What proportion of applicants are eligible?
(d) If the special honors program is limited to students whose GPAs rank in the upper 10 percent, what will Brittany’s GPA have to be for admission to this program? |
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