Manufacturing Stuff Incorporated MSI produces plastic compon

Manufacturing Stuff Incorporated (MSI) produces plastic components for the automobile industry. Previous experience shows the mean component diameter to be 52 and the standard deviation in component diameter to be 3.74. The business owner has implemented process changes intended to reduce the mean diameter but is concerned that it may have increased the standard deviation in diameter. To evaluate the situation, the owner takes a random sample of twelve plastic components made using the modified process and measures the diameter.

a) Find the appropriate value(s) to determine if the mean diameter has been reduced at 95% confidence. Can the business owner conclude the mean diameter has been reduced at 95% confidence?

b) Find the appropriate value(s) to determine if the standard deviation in diameter has increased at 95% confidence. Can the business owner conclude the standard deviation in diameter has increased at 95% confidence?

Solution