A manufacturer of doorknobs has a production process that is designed to provide a doorknob with a target diameter of 2.5 inches. In the past, the standard deviation of the diameter has been 0.035 inch.

asked Oct 27, 2021 142k views

A manufacturer of doorknobs has a production process that is designed to provide a doorknob with a target diameter of 2.5 inches. In the past, the standard deviation of the diameter has been 0.035 inch. In an effort to reduce the variation in the process, studies have been conducted that have led to a redesigned process. A sample of 25 doorknobs produced under the new process indicates a sample standard deviation of 0.025 inch. Assume diameters to be normally distributed. (a) Calculate a 99% confidence interval estimate for the variance of the redesigned process. (b) Given the results of (a), does the redesigned process result in a reduced variation