Question

10 points, 5 points for Spurrier and Thombs (1990) give data for 29 consecutive measurements on the inner diameter of a landing gear triunion. The target for the diameters is 98.00. Historically the diameters have had a standard deviation of 4. Each listed below is the average of 4 values. The data are in consecutive order reading across rows. Thus, the first observation is 101.215, the second is 98.00, and so on 97.25 103.75 00.50 109.50 97.25 101.25 96.25 99.00 93.75 98.00 97.50 02.00 01.25 101.25 98.75 97.50 95.50 93.50 95.25 93.00 85.25 94.50 102.00 99.75 100.25 92.5 95.60 95.75 99.75 (1) Calculate the upper and lower control limits for the X-chart. (Show sufficient details) (2) Plot the X-chart and comment if the process is in control

Answer 1