Question: 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, various studies have taken place that has resulted in a redesigned process. A sample of 25 doorknobs produced under the new process indicates a sample standard deviation of 0.025 inches

a) Construct and interpret a 95% confidence interval for the standard deviation of doorknobs? (10 pts)

b) At the 0.05 level of significance, is there evidence that the redesigned process has reduced the production variation (10 pts)