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2. Serum ferritin is used...

2. Serum ferritin is used in diagnosing iron deficiency. In a study conducted recently researchers discovered that in a sample of 28 elderly men the sample standard deviation of serum ferritin was 52.6 mg/L. For 26 younger men the sample standard deviation was 84.2 mg/L. At the .01 level of significance, do these data support the conclusion that the ferritin distribution in elderly men has a smaller variance than in younger men?

A.No, because the test value 1.60 is less than the critical value of 2.54

B.Yes, because the test value 0.390 is less than the critical value 2.54

C.Yes, because the test value 2.56 is greater than the critical value of 2.54

D.Yes, because the test value 2.56 is greater than the critical value 0.394

5. The correlation value ranges from A.–2 to +2 B.0 to +1 C.-3 to +3 7. An agent for a residential real estate company in a large city would like to be able to predict the monthly rental cost of apartments based on the size of the apartment. Data for a sample of 25 apartments in a particular neighborhood are provided in the worksheet Apartments in the Excel workbook Apartments.xlsx. At the .05 level of significance determine if the correlation between rental cost and apartment size is significant.

A.Yes, there is a statistically significant linear relationship between monthly rental cost and apartment size, because the sample correlation coefficient 0.85 exceeds 0.50.

B.Yes, there is a statistically significant linear relationship between monthly rental cost and apartment size, because the t-test value, 7.74, is greater than the critical value 1.96.

C.No, there is not a statistically significant linear relationship between monthly rental cost and apartment size, because the sample correlation coefficient is less than .95.

D.Yes, there is a statistically significant linear relationship between monthly rental cost and apartment size, because the p-value for this test is less than .0001.

8. In a simple linear regression analysis, the following sum of squares are produced: f$sum{(y-ar{y})^{2}}f$ = 400 f$sum{(y-y')^{2}}f$ = 80 f$sum{(y'-ar{y})^{2}}f$ = 320 The proportion of the variation in Y that is explained by the variation in X is:

A.20% B.25% C.80% D.50%

9. A field researcher is gathering data on the trunk diameters of mature pine and spruce trees in a certain area. The following are the results of his random sampling. Can he conclude, at the 0.10 level of significance, that the average trunk diameter of a pine tree is greater than the average diameter of a spruce tree? Pine trees Spruce trees Sample size 30 35 Mean trunk diameter (cm) 45 39 Sample variance 120 140 What is the test value for this hypothesis test? Test value:_______ Round your answer to three decimal places. What is the critical value? Critical value:________ Round your answer to three decimal places.

10. A company has observed that there is a linear relationship between indirect labor expense (ILE) , in dollars, and direct labor hours (DLH). Data for direct labor hours and indirect labor expense for 18 months are given in the file ILE_and_DLH.xlsx Treating ILE as the response variable, use regression to fit a straight line to all 18 data points. What values for the intercept (a) and slope (b) do you obtain? Place your answers, rounded to 3 decimal places, in the blanks provided. Do not use any stray punctuation marks. For example, 34.567 would be a legitimate entry. intercept (a) = slope(b) =

11. The marketing manager of a large supermarket chain would like to determine the effect of shelf space (in feet) on the weekly sales of international food (in hundreds of dollars). A random sample of 12 equal –sized stores is selected, with the following results: Store Shelf Space(X) Weekly Sales(Y) 1 10 2.0 2 10 2.6 3 10 1.8 4 15 2.3 5 15 2.8 6 15 3.0 7 20 2.7 8 20 3.1 9 20 3.2 10 25 3.0 11 25 3.3 12 25 3.5 Find the equation of the regression line for these data. What is the value of the standard error of the estimate? Place your answer, rounded to 3 decimal places, in the blank. Do not use a dollar sign. For example, 0.345 would be a legitimate entry.

15. The number of degrees of freedom associated with the t-test, when the data are gathered from a paired samples experiment with 12 pairs, is 24. True or False

1. A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of this trial, they wish to determine whether there is a difference between the effectiveness for women and for men. Assume α = 0.05. What is the test value? Women Men

Sample size 50 80

Mean effect 7 6.95

Sample variance 3 4

A.t = 3.252

B.z = 0.455

C.z = 0.081

D.t = 0.151

12. Are America's top chief executive officers (CEOs) really worth all that money? One way to answer this question is to look at the annual company percentage increase in revenue versus the CEO's annual percentage salary increase in that same company. Suppose that a random sample of companies yielded the following data:

percent change for corporation 15 12 3 12 28 6 8 2

percent change for CEO 6 17 -4 12 32 -1 7 2

Do these data indicate that the population mean percentage increase in corporate revenue is greater than the population mean percentage increase in CEO salary? Use a 5% level of significance. What is the critical value that you would use to conduct this test of hypothesis? Place your answer, rounded to 3 decimal places, in the blank. For example, 2.345 would be a legitimate entry.

13. An investor wants to compare the risks associated with two different stocks. One way to measure the risk of a given stock is to measure the variation in the stock’s daily price changes.

In an effort to test the claim that the variance in the daily stock price changes for stock 1 is different from the variance in the daily stock price changes for stock 2, the investor obtains a random sample of 21 daily price changes for stock 1 and 21 daily price changes for stock 2.

The summary statistics associated with these samples are: n1 = 21, s1 = .849, n2 = 21, s2 = .529.

If you follow Bluman's advice and place the larger variance in the numerator, what is the test value associated with this test of hypothesis? Place your answer, rounded to 3 decimal places, in the blank. For example, 3.456 would be a legitimate entry.

14. A professor gives an exam for which there are two versions, A and B. Each student in the class is given one randomly selected version of the exam. After the exam, the professor wishes to determine if there is a difference in the level of difficulty of the two versions by determining if there is a significant difference in the mean scores. Assume α = 0.05.

Version A Version B

Sample size 45 65

Mean score 8.8 8.2

Sample variance 2.6 2.4

What is the test value for this hypothesis test?

Answer:____ Round your answer to two decimal places.

What is/are the critical value(s) for this hypothesis test? If there are two critical values, give only the positive value.

Answer:_______ Round your answer to two decimal places.

What is the conclusion for this hypothesis test? Choose one.

1. There is not sufficient evidence to show that one version of the exam is more difficult than the other.

2. There is sufficient evidence to show that one version of the exam is more difficult than the other.

Answer: _____Enter only a 1 or 2 for your answer.

16. To help explain or predict the response variable in every regression study, we use one or more explanatory variables. These variables are also called predictor variables or independent variables.

True False

17. In a simple regression analysis, if the standard error of estimate sest = 15 and the number of observations n = 10, then the sum of the residuals squared must be 120.

True False

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