TABLE 8-3
A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired length of the insulation is 12 feet. It is known that the standard deviation in the cutting length is 0.15 feet. A sample of 70 cut sheets yields a mean length of 12.14 feet. This sample will be used to obtain a 99% confidence interval for the mean length cut by machine.
-Referring to Table 8-3, the confidence interval indicates that the machine is not working properly.

Question

TABLE 8-3 
 A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired length of the insulation is 12 feet. It is known that the standard deviation in the cutting length is 0.15 feet. A sample of 70 cut sheets yields a mean length of 12.14 feet. This sample will be used to obtain a 99% confidence interval for the mean length cut by machine.
-Referring to Table 8-3, the confidence interval indicates that the machine is not working properly.

Quizplus · Accepted Answer

The confidence interval does not include the desired mean length of 12 feet, indicating a significant deviation from the target, suggesting the machine may not be working properly.

TABLE 8-3 a Quality Control Engineer Is Interested in the Mean