1. A student wants to develop 3-sigma level variable control charts for the weight of firewood that comes in a box. Due to uneven shape of wood, weight of box varies a lot. Draw X-bar chart and R-chart using the table below. For both charts, calculate and show UCL, CL and LCL. Discuss your results. Weight in pounds from four samplings with sample size of three (n=3) are:

Sampling 1 Sampling 2 Sampling 3 Sampling 4

18 38 22 26

26 30 28 20

26 26 26 26

2. The number of weekly customer complaints are monitored in a hotel using a c-chart. Develop a 3-sigma level control chart using the data below. Calculate and show values for UCL, CL, LCL. Plot the sample data and make a conclusion. Is everything under control?

week	1	2	3	4	5
# of complaint	3	2	3	1	3

Factors for 3 Sigma level (page 195 of textbook) Sample Cortrol Limit Factor Size for Sample Macm n 2 1.880 3 1.023 4 0.729 5 0.577 10 0.308 15 0.223 20 0.180 25 0.153 Control Limit Factor for Sample Range D3 D4 0 3.267 0 2.575 0 2.282 0 2.116 0.223 1.777 0.348 1.652 0.414 1.586 0.459 1.541