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The manager of an assembly process wants to determine whether or not the number

ID: 3152716 • Letter: T

Question

The manager of an assembly process wants to determine whether or not the number of defective articles manufactured depends on the day of the week the articles are produced. She collected the following information. Is there sufficient evidence to reject the hypothesis that the number of defective articles is independent of the day of the week on which they are produced? Use = 0.05.

(a) Find the test statistic. (Give your answer correct to two decimal places.)


(ii) Find the p-value. (Give your answer bounds exactly.)
_________< p < __________

Day of Week M Tu W Th F Nondefective 95 89 93 85 91 Defective 11 13 7 15 7

Explanation / Answer

Solution:

Test statistic value = 5.1933

p-value = 0.26803

Here, we get the p-value = 0.26803 which is greater than the given level of significance so we do not reject the null hypothesis that the number of defective articles is independent of the day of the week on which they are produced.

The detailed test is given as below:

Test statistic formula = [(O – E)^2 / E]

Chi-Square Test

Observed Frequencies

Column variable

Row variable

M

Tu

W

Th

F

Total

Non-defective

95

89

93

85

91

453

Defective

11

13

7

15

7

53

Total

106

102

100

100

98

506

Expected Frequencies

Column variable

Row variable

M

Tu

W

Th

F

Total

Non-defective

94.89723

91.31621

89.52569

89.52569

87.73518

453

Defective

11.10277

10.68379

10.47431

10.47431

10.26482

53

Total

106

102

100

100

98

506

Data

Level of Significance

0.05

Number of Rows

2

Number of Columns

5

Degrees of Freedom

4

Results

Critical Value

9.487729

Chi-Square Test Statistic

5.19333

p-Value

0.26803

Do not reject the null hypothesis

Expected frequency assumption

       is met.

Chi-Square Test

Observed Frequencies

Column variable

Row variable

M

Tu

W

Th

F

Total

Non-defective

95

89

93

85

91

453

Defective

11

13

7

15

7

53

Total

106

102

100

100

98

506

Expected Frequencies

Column variable

Row variable

M

Tu

W

Th

F

Total

Non-defective

94.89723

91.31621

89.52569

89.52569

87.73518

453

Defective

11.10277

10.68379

10.47431

10.47431

10.26482

53

Total

106

102

100

100

98

506

Data

Level of Significance

0.05

Number of Rows

2

Number of Columns

5

Degrees of Freedom

4

Results

Critical Value

9.487729

Chi-Square Test Statistic

5.19333

p-Value

0.26803

Do not reject the null hypothesis

Expected frequency assumption

       is met.