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1. ###### STAT 200 Week 8 Homework
Lane – Ch. 15
10. If an experiment is conducted with 5 conditions and 6 subjects in each condition, what are dfn and dfe?
17. The following data are from a hypothetical study on the effects of age and time on scores on a test of reading comprehension. Compute the analysis of variance summary table.

 12-year-olds 16-year-olds 30 minutes 66 74 68 71 59 67 72 82 46 76 60 minutes 69 95 61 92 69 95 73 98 61 94

Illowsky – Ch. 13
Use the following information to answer the next three exercises. Suppose a group is interested in determining whether teenagers obtain their drivers licenses at approximately the same average age across the country. Suppose that the following data are randomly collected from five teenagers in each region of the country. The numbers represent the age at which teenagers obtained their drivers licenses.

 Northeast South West Central East 16.3 16.9 16.4 16.2 17.1 16.1 16.5 16.5 16.6 17.2 16.4 16.4 16.6 16.5 16.6 16.5 16.2 16.1 16.4 16.8 x-bar = ________ ________ ________ ________ ________ s^2 = ________ ________ ________ ________ ________ H0:µ1=µ2=µ3=µ4=µ5 Hα: At least any two of the group meansµ1,µ2, …,µ5are not equal.

61. degrees of freedom – numerator: df(num) = ________
63. F static = ________
69. A researcher wants to know if the mean times (in minutes) that people watch their favorite news station are the same. Suppose that Table 13.24 shows the results of a study.
CNN  FOX  Local
45    15    72
12    43    37
18    68    56
38    50    60
23    31    51
35    22      ?
Assume that all distributions are normal, the four population standard deviations are approximately the same, and the data were collected independently and randomly. Use a level of significance of 0.05.
71. Are the mean number of times a month a person eats out the same for whites, blacks, Hispanics and Asians? Suppose that Table 13.26 shows the results of a study.

 White Black Hispanic Asian 6 4 7 8 8 1 3 3 2 5 5 5 4 2 4 1 6 6 7

77. A grassroots group opposed to a proposed increase in the gas tax claimed that the increase would hurt working-class people the most, since they commute the farthest to work. Suppose that the group randomly surveyed 24 individuals and asked them their daily one-way commuting mileage. The results are as follows.

 Working-Class Professional (middles incomes) Professional (wealthy) 17.8 16.5 8.5 26.7 17.4 6.3 49.4 22 4.6 9.4 7.4 12.6 65.4 9.4 11 47.1 2.1 28.6 19.5 6.4 15.4 51.2 13.9 9.3

Determine whether or not the variance in mileage driven is statistically the same among the working class and professional (middle income) groups. Use a 5% significance level.
81. Is the variance for the amount of money, in dollars, that shoppers spend on Saturdays at the mall the same as the variance for the amount of money that shoppers spend on Sundays at the mall? Suppose that the Table 13.34 shows the results of a study.

 Saturday Sunday Saturday Sunday 75 44 62 137 18 58 0 82 150 61 124 39 94 19 50 127 62 99 31 141 73 60 118 73 89
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# STAT 200 Week 7 Homework

Lane – Ch. 142. The formula for a regression equation is Y’ = 2X + 9.
a. What would be the predicted score for a person scoring 6 on X?
b. If someone’s predicted score was 14, what was this person’s score on X?

6. For the X,Y data below, compute:
a. r and determine if it is signiﬁcantly different from zero.
b. the slope of the regression line and test if it differs signiﬁcantly from zero.
c. the 95% conﬁdence interval for the slope.

 X Y 4 6 3 7 5 12 11 17 10 9 14 21

Lane – Ch. 17
5. At a school pep rally, a group of sophomore students organized a free rafﬂe for

prizes. They claim that they put the names of all of the students in the school in

the basket and that they randomly drew 36 names out of this basket. Of the prize

winners, 6 were freshmen, 14 were sophomores, 9 were juniors, and 7 were
seniors. The results do not seem that random to you. You think it is a little ﬁshy
that sophomores organized the rafﬂe and also won the most prizes. Your school is
composed of 30% freshmen, 25% sophomores, 25% juniors, and 20% seniors.

a. What are the expected frequencies of winners from each class?
b. Conduct a signiﬁcance test to determine whether the winners of the prizes

were distributed throughout the classes as would be expected based on the

percentage of students in each group. Report your Chi Square and p values.

c. What do you conclude?

14. A geologist collects hand-specimen sized pieces of limestone from a particular

area. A qualitative assessment of both texture and color is made with the

following results. Is there evidence of association between color and texture for

 COLOR COLOR COLOR Texture Light Medium Dark Fine 4 20 8 Medium 5 23 12 Coarse 21 23 4

Illowsky – Ch. 11
True or False
70. The standard deviation of the chi-square distribution is twice the mean.
102. Do men and women select different breakfasts? The breakfasts ordered by randomly selected men and women at a popular breakfast place is shown in Table 11.55. Conduct a test for homogeneity at a 5% level of significance.

 French Toast Pancakes Waffles Omelettes Men 47 35 28 53 Women 65 59 55 60

Use the following information to answer the next twelve exercises: Suppose an airline claims that its flights are consistently on time with an average delay of at most 15 minutes. It claims that the average delay is so consistent that the variance is no more than 150 minutes. Doubting the consistency part of the claim, a disgruntled traveler calculates the delays for his next 25 flights. The average delay for those 25 flights is 22 minutes with a standard deviation of 15 minutes.
113. df= _______
117. Let a = 0.05
Decision: _______
Conclusion (write out in a complete sentence): _________
The Regression Equation
66. Can a coefficient of determination be negative? Why or why not?
82. The cost of a leading liquid laundry detergent in different
sizes is given in Table 12.31.

 Size (ounces) Cost (\$) Cost per ounce 16 3.99 32 4.99 64 5.99 100 10.99

a. Using “size” as the independent variable and “cost” as the dependent variable, draw a scatter plot.
b. Does it appear from inspection that there is a relationship between the variables? Why or why not?
c. Calculate the least-squares line. Put the equation in the form of:ŷ=a+bx
d. Find the correlation coefficient. Is it significant?
e. If the laundry detergent were sold in a 40-ounce size, find the estimated cost.
f. If the laundry detergent were sold in a 90-ounce size, find the estimated cost.
g. Does it appear that a line is the best way to fit the data? Why or why not?
h. Are there any outliers in the given data?
i. Is the least-squares line valid for predicting what a 300-ounce size of the laundry detergent would you cost? Why or why not?
j. What is the slope of the least-squares (best-fit) line? Interpret the slope