ASSIGNMENT 3: OPERATIONS MANAGEMENT 2 (PRB260S)

QUESTION 1

A Battery manufacturer has recently received complaints from retailers that its 9-volt batteries are not lasting as long as other name brands. Jabu Xulu, the Quality executive believes that there is no problem because his batteries have had an average life of 50 hours, which is about 10% longer that competitor's modes. To raise the lifetime above this level would require a new level of technology not available to this battery manufacturer. Nevertheless, he is concerned enough to set up hourly assembly line checks. Previously, after ensuring that the process was running properly, the company collected samples data of 9-volts batteries.

HOUR SAMPLES

1 2 3 4 5

1. 51 50 49 50 50

2. 45 47 70 46 36

3. 50 35 48 39 47

4. 55 70 50 30 51

5. 49 38 64 36 47

6. 59 62 40 54 64

7. 36 33 49 48 56

8. 50 67 53 43 40

9. 44 52 46 47 44

10.70 45 50 47 41

11.57 54 62 45 36

12. 56 54 47 42 62

13. 40 70 58 45 44

14. 52 58 40 52 46

15. 57 42 52 58 59

16. 62 49 42 33 55

17.40 39 49 59 48

18. 64 50 42 57 50

19. 8 53 52 48 50

20. 60 50 41 41 50

21 .52 47 48 58 40

22. 55 40 56 49 45

23. 47 48 50 50 48

24. 50 50 49 51 51

25. 51 50 51 51 62

26. 48 52 39 57 61

27. 45 53 48 46 66

28. 63 49 50 45 53

29. 57 70 45 52 61

30. 45 38 46 54 52

1.1 Which control charts must be used to analyze the above data? Justify your answer.(4)

1.2 Calculate the means and the appropriate control limits. (8)

1.3 Draw the appropriate control charts. NB: Clearly label your charts.(8)

1.4 Has the manufacturing process been in control? Why?