8.5. The following analyses, x, give the carbon content of 20 consecutive heats of 1045 steel. Three heats are made in an open hearth furnace per day. Check the control by an x chart

(with 2s limits) and a moving range chart. Specified limits are 0.45% to 0.50%. The following are given in 0.001% units: 480, 470, 470, 455, 515, 495, 460, 465, 520, 530, 485, 495, 455, 475,

515, 455, 500, 470, 480, 505.

(a) How is control?

(b) Can you estimate the proportion of heats meeting specifications?