Following are two confidence interval estimates of the mean m of the cycles to failure of an automotive door latch mechanism (the test was conducted at an elevated stress level to accelerate the failure). 3124.9 ≤ μ ≤ 3215.7 3110.5 ≤ μ ≤ 3230.1

(a) What is the value of the sample mean cycles to failure?

(b) The confidence level for one of these CIs is 95% and for the other is 99%. Both CIs are calculated from the same sample data. Which is the 95% CI? Explain why.