An injector molder produces plastic pens. The process is designed to produce pens with a mean weight of 0.250 grams. To investigate whether the injection molder is operating satisfactorily, 40 pens were randomly sample with a mean of 0.2525g and a standard deviation of .0022g.
-How would you define the rejection region for this test at ? = .001?

Question

Quizplus · Accepted Answer

The rejection region for a two-tailed test at a significance level of 0.001 corresponds to the critical t-values beyond which we reject the null hypothesis. For a large sample size, the critical z-value is approximately 3.29, but since the sample size is 40, we use the t-distribution. The critical t-value for 39 degrees of freedom at 0.001 significance level is approximately 3.558.

An Injector Molder Produces Plastic Pens