Page 456 - Six Sigma Demystified

436 Six SigMa DemystifieD

15. d.
16. a.
17. c.
18. d.
19. c.
20. a. Choices b and c are incorrect. A negative interaction implies that as one
requirement decreases, the other increases.
21. b. Cook staff training has a higher importance than number of cook staff. Choice
c is incorrect because number of cook staff has a moderate relationship with
taste, which has a customer importance of 4.
22. d.
23. b.
24. d. Step 2b1 is not on the critical path, so any improvement will not improve
capacity, nor will it improve the total delivery time.
25. b. Step 1a will remain on the critical path. The effect of moving step 2b0 to run
concurrent with step 2a is to move it off the critical path, so the cycle time for
the critical path is reduced by 1 day.
26. b.
27. c.
28. a.
29. c.
30. c.
31. d.
32. b. The average expected time for step 1 is [2 + (4 × 5) + 9]/6 = 5.17, and the
average expected time for step 2 is [4 + (4 × 8) + 13]/6 = 8.17. The sum of the
two steps then is 13.34 days.
33. c. The expected standard deviation of the cycle time for step 1 is (9 – 2)/6 =
1.17, and the expected standard deviation of the cycle time for step 2 is
(13 – 4)/6 = 1.5. The sum of the variances of the two steps then is (1.17 × 2) +
(1.5 × 2) = 3.6. The standard deviation of the two steps is the square root of
3.6 = 1.9 days.
34. d.
35. a. Walter Shewhart’s main reason for inventing the control chart technique was
to detect assignable causes of variation in the process.
36. b.
37. a.
38. b.
39. d.
40. b.
41. c.
42. d.
43. c.
44. d.
45. a.
46. c.
47. d.