Read: Six Sigma (Knowles) Chapters 1-5 – pp. 10-39; Chapters 10-12 – pp. 63-86 http://www.goleansixsigma.com/wp-content/uploads/2012/02/The-Basics-of-Lean-Six-Sigma-www.GoLeanSixSigma.com_.pdf http://

BUS4406 – Written Assignment Unit 5 Problems 1. Specifications for the density of dustless chalk used in classrooms is 3.5 ± 1.5. (The unit of measure is grams per centimeter2, or g/cm2.) A random sample of 100 pieces of chalk was selected and the density of each piece in the sample was recorded. The sample average was equal to 3.6 and the sample standard deviation was eq ual to 0.75. A histogram of the sample data is given below. a. How many pieces of chalk in the sample are considered defective (not within the specifications)? b. Using your response to the above question, what is the dpmo value for this process? c. According to the concepts of Six -Sigma Quality, what the quality level for this process? (Use the conversion table provided.) 0 2 4 6 8 10 12 14 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 Density Frequency 2. The number of defects found in 20 samples of 100 Frost Ice -cream Company flavors taken on a daily basis from a production line over a five -we ek period is given below. Sample Defects 1 3 2 8 3 6 4 9 5 7 6 1 7 9 8 3 9 6 10 7 11 11 12 14 13 7 14 8 15 4 16 5 17 2 18 4 19 6 20 1 a. Plot these data on a run chart, computing the average value (center line ). b. According to the concepts of Six -Sigma Quality, what the quality level for this process? (Use the conversion table provided.) c. Do you suspect that any special causes are present? Why? 3. Analysis of customer complaints at Flash Apparel Company revealed errors in five categories. Data is provided below. Errors Frequency Billing errors 960 Shipping errors 3628 Electronic charge errors 530 Long delays 5793 Delivery errors 651 Total 11562 a. Construct a Pareto diagram for these data. b. What conclusions can you reach? 4. A machine produces rubber tubing of a set length: as the conveyor moves the tube, a blade cuts it at regular intervals. The customer specification for the tube length is 1026 mm, +/ - 10 mm. However, t here is an inconsistency in the cut length of the rubber tubes produced, so data is sampled measuring the conveyor speed and cut length. The results are showed in the table bel ow. Number Conveyor Speed (cm/sec) Cut Length (mm) Number Conveyor Speed (cm/sec) Cut Length (mm) 1 8.1 1046 26 8 1040 2 7.9 1030 27 5.5 1013 3 8 1039 28 6.9 1025 4 7.4 1027 29 7 1020 5 7.5 1028 30 7.5 1022 6 7.4 1025 31 6.7 1020 7 8 1035 32 8.1 1035 8 7.2 1015 33 9 1052 9 8 1038 34 7.1 1021 10 7.9 1036 35 7.6 1024 11 7.6 1026 36 8.5 1029 12 8 1041 37 7.5 1015 13 7.5 1029 38 8 1030 14 7.2 1010 39 5.2 1010 15 7.3 1020 40 6.5 1025 16 7.4 1024 41 8 1031 17 8 1034 42 6.9 1030 18 8 1036 43 7.6 1034 19 7.4 1023 44 6.5 1034 20 7.1 1011 45 5.5 1020 21 7.9 1030 46 6 1025 22 7.3 1014 47 5.5 1023 23 7.8 1030 48 7.6 1028 24 7.2 1016 49 8.6 1020 25 7.3 1020 50 6.3 1026 a. Construct a run chart for this data. What conclusions can you reach? b. According to the concepts of Six -Sigma Quality, what the quality level for this process? (Use the conversion table provided.) c. Construct a scatter diagram for the data provided. What conclusions can you reach? d. What recommendations would you make to improve this process?