Juan Valdez sells bags of coffee labeled "16 ounces". He wonders if the machine that weighs and bags the beans is properly aligned. He selects a random sample of 28 bags, which contain an average of 15.8 ounces with a standard deviation of .48 ounces. Test whether the machine is working within specification.

Weight

16.081

15.483

15.405

15.665

15.329

15.328

15.273

16.282

15.523

16.167

15.902

16.463

15.732

16.071

15.361

16.016

16.146

15.302

15.552

16.475

15.551

16.777

15.974

15.621

15.710

14.703

16.670

15.837

Test whether the process is out of control in either direction at the .01 level of significance.

Assumptions Checks:

Normality: p = ____ Met (ns).___ Violated (p < .01) ____ (check one)

Select the appropriate statistic

Test: _______

State the Null and the Alternative Hypothesis

Null: H0: _______

Alt: H1: ______

Select a level of significance

Tails: ______-tail test, = _________

CV: CV(27; .01) = ___________

Calculate the Statistics

Stats: t(27) = _______, p < _______, 99% CI[______, _______]

Descriptives: N = _______, M = _________, SD = _________, SE = _________

Make the decision!

Decision:

Reject the null or fail to reject? _________

Is the process out of control? __________

Are the coffee bags too light, too heavy, within specification? __________

What is the 95% confidence interval (not 99%)? 95% CI[__________, __________]

Would the test be statistically significant at the .05 level? _________

What would the critical value be if you set = .05? _________