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In: Statistics and Probability

Question Manufacturers are testing a die to make sure that it is fair (has a uniform...

Question

Manufacturers are testing a die to make sure that it is fair (has a uniform distribution). They roll the die 84 times and record the outcomes in the table below.

Outcome 1 2 3 4 5 6
Expected 14 14 14 14 14 14
Observed 17 12 15 5 16 19

They perform a chi-square Goodness-of-Fit Test. The first few steps are summarized below.

  • H0: The die is fair.
    Ha: The die is not fair.
  • α=0.01
  • The test statistic, χ20=8.857.

Use the following portion of the χ2-table for the critical value.

df χ20.10 χ20.05 χ20.025 χ20.01 χ20.005
...
4 7.779 9.488 11.143 13.277 14.860
5 9.236 11.070 12.833 15.086 16.750
6 10.645 12.592 14.449 16.812 18.548
7 12.017 14.067 16.013 18.475 20.278
8 13.362 15.507 17.535 20.090 21.955


Which is the correct conclusion of our goodness-of-fit test, at the 1% significance level?

Select the correct answer below:

Degrees of freedom =5.

Critical value: χ20.01=16.750.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should reject H0 because the test statistic falls in the rejection region (less than χ20.01).

Degrees of freedom =5.

Critical value: χ20.01=15.086.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should reject H0 because the test statistic falls in the rejection region (less than χ20.01).

Degrees of freedom =6.

Critical value: χ20.01=18.548.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should reject H0 because the test statistic falls in the rejection region (less than χ20.01).

Degrees of freedom =5.

Critical value: χ20.01=15.086.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should not reject H0 because the test statistic does not fall in the rejection region (greater than χ20.01).

Degrees of freedom =6.

Critical value: χ20.01=16.812.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should not reject H0 because the test statistic does not fall in the rejection region (greater than χ20.01).

Degrees of freedom =5.

Critical value: χ20.01=16.750.

Conclusion: The test statistic is less than the critical value χ20<χ20.01. So, we should not reject H0 because the test statistic does not fall in the rejection region (greater than χ20.01).

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