# Question

A large order of the no. 9 corks described in Applied Example 6.13 (p. 285) is about to be shippe

d. The final quality-control inspection includes an estimation of the mean ovality (ovalization; out-ofroundness) of the corks. The diameter of each cork is measured in several places, and the difference between the maximum and minimum diameters is the measure of ovality for each cork. After years of measuring corks, the manufacturer is sure that ovality has a mounded distribution with a standard deviation of 0.10 mm. A random sample of 36 corks is taken from the batch and the ovality is determined for each.

a. The out-of-round spec is “less than 1.0 mm.” Does it appear this order meets the spec on an individual cork basis? Explain.

b. The certification sheet that accompanies the shipment includes a 95% confidence interval for the mean ovality. Construct the confidence interval.

c. Explain what the confidence interval found in part b tells about this shipment of corks.

d. The final quality-control inspection includes an estimation of the mean ovality (ovalization; out-ofroundness) of the corks. The diameter of each cork is measured in several places, and the difference between the maximum and minimum diameters is the measure of ovality for each cork. After years of measuring corks, the manufacturer is sure that ovality has a mounded distribution with a standard deviation of 0.10 mm. A random sample of 36 corks is taken from the batch and the ovality is determined for each.

a. The out-of-round spec is “less than 1.0 mm.” Does it appear this order meets the spec on an individual cork basis? Explain.

b. The certification sheet that accompanies the shipment includes a 95% confidence interval for the mean ovality. Construct the confidence interval.

c. Explain what the confidence interval found in part b tells about this shipment of corks.

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