Drill lifetime: A sample of 50 drills had a mean lifetime of 12.54 holes drilled when drilling a low-carbon steel. Assume the population standard deviation is 7.11. Part: 0 / 3 Part 1 of 3 (a)...

Extracted text: Drill lifetime: A sample of 50 drills had a mean lifetime of 12.54 holes drilled when drilling a low-carbon steel. Assume the population standard deviation is 7.11. Part: 0 / 3 Part 1 of 3 (a) Construct a 95% confidence interval for the mean lifetime of this type of drill. Use tables or technology. Round your answers to at least two decimal places. OD. The confidence interval is Part: 1 / 3 Part 2 of 3 (b) The manufacturer of the drills claims that the mean lifetime is greater than 13. Does this confidence interval contradict this claim? the confidence interval (Choose one) |(Choose one) |(Choose one) is is not values greater than 13, so the claim contradicted.


Extracted text: Drill lifetime: A sample of 50 drills had a mean lifetime of 12.54 holes drilled when drilling a low-carbon steel. Assume the population standard deviation is 7.11. Part: 0 / 3 Part 1 of 3 (a) Construct a 95% confidence interval for the mean lifetime of this type of drill. Use tables or technology. Round your answers to at least two decimal places. The confidence interval is ( ). Part: 1 / 3 Part 2 of 3 (b) The manufacturer of the drills claims that the mean lifetime is greater than 13. Does this confidence interval contradict this claim? |(Choose one) the confidence interval (Choose one) values greater than 13, so the claim (Choose one) contradicted. contains some does not contain any