Drill lifetime: A sample of 50 drills had a mean lifetime of 12.88 holes drilled when drilling a low-carbon steel. Assume the population standard deviation is 5.31. 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 11.13 14.63 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) v values greater than 13, so the claim (Choose one) (Choose one) contradicted.

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