Question 1 (a) Discuss what is nuisance factor using examples from your experience conducting experiment. (3 marks) (b) Illustrate the differences between coded mathematical model and natural mathematical model. You may use general mathematical model as an example. (3 marks) (c) Fig. 1 shows the results of a tool life experiment when cutting mild steel. Explain the effect of changing Bit size from low (-1) to high (+) and the effect of changing Cutting speed from low (-1) to high (+). Do the results of the experiment indicate with interaction or without interaction experiment? Provide proof for your conclusion. 16 42 (High) Cutting Speed, B (Low) 18 26 (Low) (High) Bit size, A Fig 1: 2-factor effect plot (8 marks)