1. You spent your engineering internship training last year in a textile manufacturing company Smart Textile Sdn. Bhd. in Negeri Sembilan. Recently, the Quality Manager of that company, En. Qua Lee Tee contacted you for some help in deciding a new supplier of fabric to his company. Receiving lots of fabric from the supplier, Mr. Tee wants to know if the lot average breaking strength exceeds 1.38 MPa for him to accept the lot. a. With your quality training, suggest what he should do. b. If Mr. Tee also provided you past records (of other inspectors) indicating that a reasonable value for the variance of fabric breaking strength was 0.69 MPa and the average breaking strength of four specimens equals 1.48 MPa, help Mr. Tee to reach some conclusion(s). c. Explain clearly what you would do if the variance of the population of the fabric is unknown. 2. In addition to the request in 1. above, Mr. Tee the Quality Manager also provided you with some information and data of the experiments done to develop a new textile product (see the table below). According to him, the company is interested in investigating the tensile strength of a new synthetic fiber that will be used to make cloth for designer's shirt. Mr. Tee explained that from previous experience that the strength is affected by the weight percent of polyester used in the blend of materials for fiber. Furthermore, Mr. Tee suspected that increasing the polyester content will increase the strength, at least initially. He advised that content of polyester should be between about 10 and 40 percent if the final product is to have other desired quality attributes. Mr. Tee shared with you the test results of specimens at five levels of polyester weight percent: 15, 20, 25, 30 and 35 percent. According to him, the tests were carried on five specimens at each level of polyester content. Polyester Weight (%) 20 15 35 Tensile Strength (MPa) 18 15 10 2 1 Test Run Sequence Number 8 18 3 10 4 23 S 17 6 5 7 14 8 6 9 15 10 20 11 9 12 4 13 12 Table Experimental details and results Polyester Tensile Run Weight Test Strength (MPa) Sequence Number 20 12 14 30 19 15 20 17 16 24 35 7. 17 21 30 25 18 11 15 7 19 25 14 20 13 20 12 21 22 25 18 22 16 30 22 23 25 20 18 24 19 15 7 25 3 25 18 15 19 11 19 15 19 11 23 9 30 35 30 15 Page 1 of 2 a. Discuss the importance of what you see in Column 2 of the table. b. Draw using box plots the tensile strength versus polyester weight percentage. Discuss. c. Help Mr. Tee to make some conclusion(s) about his product development experiments 3. Discuss your understanding of the Design of Experiments tool and terms of its strengths and general applications