Answer Happy

Efficient manufacturing: Efficiency experts study the processes used to manufacture items in order to make them as efficient as possible. One of the steps used to manufacture a metal clamp involves the drilling of three holes. In a sample of 90 clamps, the mean time to complete this step was 58.4 seconds. Assume that the population standard deviation is a = 10 seconds. Round the critical value to no less than three decimal places. Part 1 of 2 (a) Construct an 80% confidence interval for the mean time needed to complete this step. Round the answer to at least one decimal place. An 80% confidence interval for the mean is 57.05 <μ< 59.75 Part: 1/2 Part 2 of 2 (b) Find the sample size needed so that a 99.5% confidence interval will have margin of error of 1.5. A sample size of is needed in order to obtain a 99.5% confidence interval with a margin error of 1.5. Round the sample size up to the nearest integer.