Q12

1. The data below represents the points gained or lost (a positive number indicates a gain and a negative number indicates a loss) yesterday for various stocks on the New York Stock Exchange at

different times throughout the day. The question would be to test if the data suggests that the mean gain(or loss) is the same for the three companies. At a 5% level of significance, give the between-group variance.

Microsoft

Maytag

John Deere

-2.1

5.7

-4.8

8.4

-4.1

6.4

7.9

1.2

5.9

-9.5

7.6

-8.2

5.3

7.7

1. The newspaper, USAToday, wants to compare the average lifetimes of calculator batteries of three different types. The magazine takes a random sample of batteries and determines their lifetimes in hours. The following table shows the information for each type. At the .05 level of significance, give the within-group variance.

DURA

EVER

PANA

260

161

283

238

290

267

124

172

286

209

258

1. At the 0.025 significance level, test the claim that the three categories, R, S, and T, have the same mean if the following sample results have been obtained.

R

S

T

32

57

32

44

84

12

57

22

11

25

1. In three sections of statistics last year, I gave a 100-point test. The following table shows samples of scores from those sections. Test the claim that the sections scored the same average. Use a .025 level of significance.

Class D

Class E

Class F

87

60

56

90

74

94

82

68

62

70

72

64

76

63

80

84

1. Three categories are to be tested, at a 5% level of significance, to see if they have the same averages. The data appears in the table below. Give the test stat that would be used for this test.

A

B

C

12

5

6

6

2

4

3

1. A vending machine company wants to check three of its machines to determine if they are properly dispensing 12 ounces of beverage. The plan is to use a 5% significance level to test the belief that there is a difference in the mean amount of beverage for the three machines. The table below gives the data. What is the grand mean?

Machine A

Machine B

Machine C

11.8

11.7

12.2

12.1

11.9

12.1

11.7

12

1. A store manager wants to see if there is a difference in the average time (in minutes) a customer has to wait in line for 4 of her checkers. At a 2.5% level of significance, what is the critical value?

Checker 1

Checker 2

Checker 3

Checker 4

3

3

2

2

5

5

3

3

4

2

5

4

6

3

6

4

7

4

3

5

1. The head of the English department wants to determine if the average number of students taking English classes differs depending on the time of the day the course is being offered. The data is given in the table below. Give the test stat if ? = 0.05.

Morning

Afternoon

Evening

25

25

27

26

24

26

27

18

26

1. There are 6 categories that contain a total of 35 data values. Give the critical value if an ANOVA test is to be used to test for equality of means at a 5% level of significance.

2. A set of 12 data values from category C have a sum of 357, a set of 15 data values from category D have a sum of 289, a set of 11 data values from category E have a sum of 158, and a set of 13 data values from category F have a sum of 98. Give the grand mean.