A manufacturing operation consists of a unique system that produces an average of 15.5 jet engine propulsion parts every hour. After undergoing a complete overhaul, the system was monitored by observing the number of parts produced in each of 17 randomly selected one-hour periods. The mean is 15.42 with a standard deviation of 0.16. Assume the number of parts produced is approximately normal.
-How would you define the rejection region for this test at ? = .10?

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Quizplus · Accepted Answer

For a two-tailed test with α = .10, the critical values from the t-distribution are found at the 5% and 95% percentiles because the test is split into two tails. The degrees of freedom (df) are 16 (17 - 1). Looking up a t-table or using a calculator for the 90% confidence interval (or 10% significance level) with 16 df gives a t-value around ±1.746. This defines the rejection region for values of t that are greater than 1.746 or less than -1.746.

A Manufacturing Operation Consists of a Unique System That Produces