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free/or 0.5$ |
| m486 | A group of 10,000 people are tested for a gene called Ifi202 that has been found to increase the risk for lupus. The random variable is the number of people who carry the gene. |
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| m487 | Health issues are a concern of managers, especially as they evaluate the cost of medical insurance. A recent survey of 150 executives at Elvers Industries, a large insurance and financial firm located in the Southwest, reported the number of pounds by which the executives were overweight. Compute the mean and the standard deviation.
Pounds Overweight Frequency
0 up to 6.......... 14
6 up to 12.......... 42
12 up to 18.......... 58
18 up to 24......... 28
24 up to 30.......... 8 |
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| m488 | hen only two treatments are involved, ANOVA and the Student’s t test (Chapter) result in the same conclusions. Also, t2 = F. As an example, 14 randomly selected Introduction to History students were divided into two groups, one consisting of 6 students and the other of 8. One group took the course in the normal lecture format. The other group of 8 students took the course via the Internet. At the end of the course, each group was given a 50-item test. The following is a list of the number correct for each of the two groups.
Traditional Lecture Internet
19 ............. 32
17 ............. 28
23 ............. 31
22 ............. 26
17 ............. 23
16 ............. 24
27
25
a. Using analysis of variance techniques, test H0 that the two mean test scores are equal; α = .05.
b. Using the t test from Chapter 11, compute t.
c. Interpret the results. |
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| m489 | Here is a table showing the number of employed and unemployed workers 20 years or older by gender in the United States.
a. How many workers were studied?
b. What percent of the workers were unemployed?
c. Compare the percent unemployed for the men and thewomen. |
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| m490 | Historically, Widgets Manufacturing Inc. produces 250 widgets per day. Recently the new owner bought a new machine to produce more widgets per day. A sample of 16 days’ production revealed a mean of 240 units with a standard deviation of 35. Construct a confidence interval for the mean number of widgets produced per day. Does it seem reasonable to conclude that the mean daily widget production has changed? Justify your conclusion. |
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| m491 | Horwege Electronics Inc. purchases TV picture tubes from four different suppliers. Tyson Wholesale supplies 20% of the tubes, Fuji Importers 30%, Kirkpatricks 25%, and Parts Inc. 25%. Tyson Wholesale tends to have the best quality, as only 3% of its tubes arrive defective. Fuji Importers’ tubes are 4% defective, Kirkpatricks’ 7%, and Parts Inc.’s are 6.5% defective.
a. What is the overall percent defective?
b. A defective picture tube was discovered in the latest shipment. What is the probability that it came from Tyson Wholesale? |
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| m492 | Hugger Polls contends that an agent conducts a mean of 53 in-depth home surveys every week. A streamlined survey form has been introduced, and Hugger wants to evaluate its effectiveness. The number of in-depth surveys conducted during a week by a random sample of 15 agents are:
At the .05 level of significance, can we conclude that the mean number of interviews con-ducted by the agents is more than 53 per week? Estimate thep-value. |
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| m493 | Human Resource Consulting (HRC) surveyed a random sample of 60 Twin Cities construction companies to find information on the costs of their health care plans. One of the items being tracked is the annual deductible that employees must pay. The Minnesota Department of Labor reports that historically the mean deductible amount per employee is $502 with a standard deviation of $100.
a. Compute the standard error of the sample mean for HRC.
b. What is the chance HRC finds a sample mean between $477 and $527?
c. Calculate the likelihood that the sample mean is between $492 and $512.
d. What is the probability the sample mean is greater than $550? |
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| m494 | IBM Inc. is going to award a contract for fine-line pens to be used nationally in its offices. Two suppliers, Bic and Pilot, have submitted bids. To determine the preference of office employees, brokers, and others, a personal preference test is to be conducted using a randomly selected sample of 20 employees. The .05 level of significance is to be used.
a. If the alternate hypothesis states that Bic is preferred over Pilot, is the sign test to be conducted as a one-tailed or a two-tailed test? Explain.
b. As each of the sample members told the researchers his or her preference, a “1” was recorded if it was Bic and a “2” if it was the Pilot fine-line pen. A count of the pluses revealed that 12 employees preferred Bic, 5 preferred Pilot, and 3 were undecided. What is n?
c. What is the decision rule in words?
d. What conclusion did you reach regarding pen preference? Explain. |
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| m496 | If A, B, and C are mutually exclusive events with P(A) = 0.2, P (B) =0.3, and P(C) = 0.4, determine the following probabilities:
(a) P (A U B U C)
(b) P (A ∩ B ∩ C)
(c) P (A ∩ B)
(d) P [(A U B) ∩ C]
(e) P (A’ ∩ B’ ∩ C’) |
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| m497 | If A, B, and C are mutually exclusive events, is it possible for P (A) = 0.3, P (B) = 0.4, and P (C) = 0.5? Why or why not? |
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| m516 | If P (A) = 0.2, P (B) = 0.2, and A and B are mutually exclusive, are they independent? |
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| m517 | If P (A) = 0.3, P (B) = 0.2, and P (A U B) = 0.1, determine the following probabilities:
(a) P (A’)
(b) P (A U B)
(c) P (A` ∩ B)
(d) P (A ∩ B’)
(e) P [(A U B’)]
(f) P (A` U B) |
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| m518 | If P (A|B) = 0.3, P (B) = 0.8, P (A) = 0.3, and are the events B and the complement of A independent? |
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| m519 | If P (A|B) = 0.4, P (B) = 0.8, P (A) = 0.5, are the events A and B independent? |
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| m520 | If P (A|B) = 1, must A = B? Draw a Venn diagram to explain your answer. |
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| m521 | If plotted, the following sales series would appear curvilinear. This indicates that sales are increasing at a somewhat constant annual rate (percent). To fit the sales, therefore, a logarithmic equation should be used.
a. Determine the logarithmic equation.
b. Determine the coordinates of the points on the logarithmic straight line for 2005 and 2011.
c. By what percent did sales increase per year, on the average, during the period from 2004 to 2014?
d. Based on the equation, what are the estimated sales for2015? |
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| m522 | A dry cleaning establishment claims that a new spot remover will remove more than 70% of the spots to which it is applied. To check this claim, the spot remover will be used on 12 spots chosen at random. If fewer than 11 of the spots are removed, we shall not reject the null hypothesis that p = 0.7: otherwise, we conclude that p > 0.7.
(a) Evaluate a, assuming that p = 0.7.
(b) Evaluate 8 for the alternative p = 0.9. |
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| m524 | If the last digit of a weight measurement is equally likely to be any of the digits 0 through 9,
(a) What is the probability that the last digit is 0?
(b) What is the probability that the last digit is greater than or equal to 5? |
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| m525 | If the range of X is the set {0, 1, 2, 3, 4} and P(X =x) =0.2 determine the mean and variance of the random variable. |
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