26.A population proportion is to be estimated. Estimate the minimum sample size needed to achieve a margin of error E = 0.01with a 95% degree of confidence.
A. 7,000 B. 8,000 C. 9,000 D. 10,000
n = p(1p)(z/E)^{2} = (0.5)(0.5)(2/0.01)^{2} = 10,000
27. Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.
A. 0.9 

B. 0.1 

C. 0.5 

D. 0.9
The slope of the regression line is negative, so the coefficient of correlation must
also be negative.
28. A sample of nine students is selected from among the students taking a particular exam. The nine students were asked how much time they had spent studying for the exam and the responses (in hours) were as follows:18, 7, 10, 13, 12, 16, 5, 20, 21
Estimate the mean study time of all students taking the exam. Round your answer to the nearest tenth of an hour if necessary. A. 13 hours B. 12.2 hours C. 13.6 hours
D. It is not possible to estimate the population mean from this sample data
Mean = (18 + 7 + 10 + 13 + 12 + 16 + 5 + 20 + 21) / 9 = 13.6
29. The scatter plot and bestfit line show the relation among the data for the price of a stock (y) and employment (x) in arbitrary units. The correlation coefficient is 0.8. Predict the stock price for an employment value of 6.
A. 8.8 

B. 6.2 

C. 8.2 

D. None of the values are correct
Draw a vertical line through “6” on the horizontal axis, and extend the line vertically until it intersects the line on the graph. Then draw a horizontal line through the point of intersection and extend that line to the left until it intersects the vertical axis. Read the value from the vertical axis, which is about 6.2.
30.The graph shows a measure of fitness (y) and miles walked weekly. Identify the probable cause of the correlation.
A. The correlation is coincidental. 

B. There is a common underlying cause of the correlation. 

C. There is no correlation between the variables. 

D. Walking is a direct cause of the fitness.
31. Eleven female college students are selected at random and asked their heights. The heights (in inches) are as follows:67, 59, 64, 69, 65, 65, 66, 64, 62, 64, 62Estimate the mean height of all female students at this college. Round your answer to the nearest tenth of an inch if necessary.
A. It is not possible to estimate the population mean from this sample data 

B. 64.3 inches 

C. 64.9 inches 

D. 63.7 inches
Mean = (67 + 59 + 64 + 69 + 65 + 65 + 66 + 64 + 62 + 64 + 62) / 11 = 64.3
32. Select the best fit line on the scatter diagram below.
A. A 

B. B 

C. C 

D. All of the lines are equally good
33. In a poll of 400 voters in a certain state, 61% said that they opposed a voter ID bill that might hinder some legitimate voters from voting. The margin of error in the poll was reported as 4 percentage points (with a 95% degree of confidence). Which statement is correct?
A. The reported margin of error is consistent with the sample size.
B. There is not enough information to determine whether the margin of error is consistent with the sample size.
C. The sample size is too small to achieve the stated margin of error.
D. For the given sample size, the margin of error should be smaller than stated 

Required sample size = (phat)(1 – phat)(z/E)^{2} = (0.61)(1 – 0.61)(2/0.04)^{2} = 594.75
34.The scatter plot and bestfit line show the relation among the number of cars waiting by a school (y) and the amount of time after the end of classes (x) in arbitrary units. The correlation coefficient is 0.55. Determine the amount of variation in the number of cars not explained by the variation time after sch
A. 55% 

B. 70% 

C. 30% 

D. 45%
Coefficient of nondetermination = 1 – r^{2} = 1 – (0.55)^{2} = 0.6975 → 70%
35. Which graph has two groups of data, correlations within each group, but no correlation among all the data?
A.


B.


C.


D
36. The scatter plot and bestfit line show the relation among the number of cars waiting by a school (y) and the amount of time after the end of classes (x) in arbitrary units. The correlation coefficient is 0.55. Use the line of best fit to predict the number of cars at time 4 after the end of classes.
A. 7.0 

B. 6.0 

C. 8.0 

D. 3.5 






