A bolt manufacturer is using a hypothesis test with = 0.01 to see if the diamete

ID: 3131550 • Letter: A

Question

A bolt manufacturer is using a hypothesis test with = 0.01 to see if the diameter of

their 0.75 cm diameter bolts are being manufactured properly. The goal is to have the

average bolt diameter be 0.75 ± 0.0075 cms. (Thus, a 2-sided test with difference of

0.0075 is used.) They know that the standard deviation of the 0.75 cm bolts is 0.028

cms. Use Minitab to compute the sample size necessary to achieve a power of 0.9.

According to the Power Curve, if a difference of 0.0025 must be used, what is the

approximate power of the test using this sample size? Copy and paste or attach your

Minitab output to your paper.

1-Sample t Test

Testing mean = null (versus null) Calculating power for mean = null + difference = 0.01

Assumed standard deviation = 0.0075 Sample size= 242 Target Power (0.9) Actual Power (0.900854)

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