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free/or 0.5$ |
| m63 | A new machine has just been installed to cut and rough-shape large slugs. The slugs are then transferred to a precision grinder. One of the critical measurements is the outside diameter. The quality control inspector randomly selected five slugs each half-hour, measured the outside diameter, and recorded the results. The measurements (in millimeters) for the period 8:00 a.m. to 10:30 a.m. follow.
a. Determine the control limits for the mean and the range.
b. Plot the control limits for the mean outside diameter and the range.
c. Are there any points on the mean or the range chart that are out of control? Comment on thechart. |
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| m64 | A new sports car model has defective brakes 15% of the time and a defective steering mechanism 5% of the time. Let’s assume (and hope) that these problems occur independently. If one or the other of these problems is present, the car is called a “lemon.” If both of these problems are present, the car is a “hazard.” Your instructor purchased one of these cars yesterday. What is the probability it is:
a. A lemon?
b. A hazard? |
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| m65 | A new weight-watching company, Weight Reducers International, advertises that those who join will lose, on the average, 10 pounds the first two weeks with a standard deviation of 2.8 pounds. A random sample of 50 people who joined the new weight reduction program revealed the mean loss to be 9 pounds. At the .05 level of significance, can we conclude that those joining Weight Reducers on average will lose less than 10 pounds? Determine the p-value. |
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| m66 | A normal distribution has a mean of 50 and a standard deviation of 4.
a. Compute the probability of a value between 44.0 and 55.0.
b. Compute the probability of a value greater than 55.0.
c. Compute the probability of a value between 52.0 and 55.0. |
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| m67 | A normal population has a mean of 12.2 and a standard deviation of 2.5.
a. Compute the z value associated with 14.3.
b. What proportion of the population is between 12.2 and 14.3?
c. What proportion of the population is less than 10.0? |
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| m68 | A normal population has a mean of 20.0 and a standard deviation of 4.0.
a. Compute the z value associated with 25.0.
b. What proportion of the population is between 20.0 and 25.0?
c. What proportion of the population is less than 18.0? |
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| m69 | A normal population has a mean of 60 and a standard deviation of 12. You select a random sample of 9. Compute the probability the sample mean is:
a. Greater than 63.
b. Less than 56.
c. Between 56 and 63. |
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| m70 | A normal population has a mean of 75 and a standard deviation of 5. You select a sample of 40. Compute the probability the sample mean is:
a. Less than 74.
b. Between 74 and 76.
c. Between 76 and 77.
d. Greater than 77. |
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| m71 | A normal population has a mean of 80.0 and a standard deviation of 14.0.
a. Compute the probability of a value between 75.0 and 90.0.
b. Compute the probability of a value of 75.0 or less.
c. Compute the probability of a value between 55.0 and 70.0. |
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| m72 | A number of minor automobile accidents occur at various high-risk intersections in Teton County despite traffic lights. The Traffic Department claims that a modification in the type of light will reduce these accidents. The county commissioners have agreed to a proposed experiment. Eight intersections were chosen at random, and the lights at those intersections were modified. The numbers of minor accidents during a six-month period before and after the modifications were:
At the .01 significance level, is it reasonable to conclude that the modification reduced the number of trafficaccidents? |
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| m73 | A population consists of the following five values: 0, 0, 1, 3, 6.
a. List all samples of size 3, and compute the mean of each sample.
b. Compute the mean of the distribution of sample means and the population mean. Compare the two values.
c. Compare the dispersion in the population with that of the sample means. |
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| m74 | A population consists of the following five values: 12, 12, 14, 15, and 20.
a. List all samples of size 3, and compute the mean of each sample.
b. Compute the mean of the distribution of sample means and the population mean. Compare the two values.
c. Compare the dispersion in the population with that of the sample means. |
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| m75 | A population consists of the following five values: 2, 2, 4, 4, and 8.
a. List all samples of size 2, and compute the mean of each sample.
b. Compute the mean of the distribution of sample means and the population mean. Compare the two values.
c. Compare the dispersion in the population with that of the sample means. |
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| m76 | A population consists of the following four values: 12, 12, 14, and 16.
a. List all samples of size 2, and compute the mean of each sample.
b. Compute the mean of the distribution of the sample mean and the population mean.
Compare the two values.
c. Compare the dispersion in the population with that of the sample mean. |
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| m77 | A population consists of the following three values: 1, 2, and 3.
a. Sampling with replacement, list all possible samples of size 2 and compute the mean of every sample.
b. Find the means of the distribution of the sample mean and the population mean. Compare the two values.
c. Compare the dispersion of the population with that of the sample mean.
d. Describe the shapes of the two distributions. |
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| m78 | A process engineer is considering two sampling plans. In the first, a sample of 10 will be selected and the lot accepted if 3 or fewer are found defective. In the second, the sample size is 20 and the acceptance number is 5. Develop an OC curve for each. Compare the probability of acceptance for lots that are 5, 10, 20, and 30% defective. Which of the plans would you recommend if you were the supplier? |
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| m79 | A quality control inspector selects a part to be tested. The part is then declared acceptable, repairable, or scrapped. Then another part is tested. List the possible outcomes of this experiment regarding two parts. |
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| m80 | A real estate agent in the coastal area of Georgia wants to compare the variation in the selling price of homes on the oceanfront with those one to three blocks from the ocean. A sample of 21 oceanfront homes sold within the last year revealed the standard deviation of the selling prices was $45,600. A sample of 18 homes, also sold within the last year, that were one to three blocks from the ocean revealed that the standard deviation was $21,330. At the .01 significance level, can we conclude that there is more variation in the selling prices of the oceanfront homes? |
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| m81 | A real estate developer is considering investing in a shopping mall on the outskirts of Atlanta, Georgia. Three parcels of land are being evaluated. Of particular importance is the income in the area surrounding the proposed mall. A random sample of four families is selected near each proposed mall. Following are the sample results. At the .05 significance level, can the developer conclude there is a difference in the mean income? Use the usual six-step hypothesis testingprocedure. |
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| m82 | A real estate developer wishes to study the relationship between the size of home a client will purchase (in square feet) and other variables. Possible independent variables include the family income, family size, whether there is a senior adult parent living with the family (1 for yes, 0 for no), and the total years of education beyond high school for the husband and wife. The sample information is reported below.
Develop an appropriate multiple regression equation. Which independent variables would you include in the final regression equation? Use the stepwisemethod. |
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