4. In filling bags of nitrogen fertilizer, it is desired to hold the average over fill to as low a value as possible. The lower specification limit is 22.00 kg, the population mean weight of the bags is 22.73 kg, and the population standard deviation is 0.80 kg. Assuming a normal distribution: a. What percent of the bags contain less than 22 kg? b. If it is permissible for 5% of the bags to be below 22 kg, what would be the average weight? 5. The following data is a result of the Brinell hardness of hardened tool steel in kilograms per square millimeter. Data of subgroup sizes of 8 are shown below. Determine the trial centerline and control limits. Assume that the out-of-control points have assignable causes. Subgroup # 1 X-bar S 540 26 2 534 23 3 545 24 561 27 5 576 25 6 523 50 7 571 29 8 547 29 9 584 23 10 552 24