Logistics Engineering IV (LSE400S) DISE-CPUT Tutorial 2: Reliability Page 1 of 2

Blanchard, Benjamin S. Logistics Engineering & Management: Pearson New International Edition, 6th Edition. Pearson (Intl), 10/2013. pp 76-77

Answer the following questions:

1. Define reliability. What are its major characteristics?

2. Refer to Figure 1. What is the probability of success for a system if the system MTBF is 600 hours and the mission operating time is 420 hours? (Assume exponential distribution.)

3. A system consists of four subassemblies connected in series. TI1e individual subassembly reliabilities are as follows: Subassembly A = 0.98

Subassembly B = 0.85

Subassembly C = 0.90

Subassembly D = 0.88

Determine the overall system reliability.

4. A system consists of three subsystems in parallel (assume operating redundancy). The individual subsystem reliabilities are as follows: Subsystem A = 0.98

Subsystem B = 0.85

Subsystem C = 0.88

Determine the overall system reliability.

5. Refer to Figure 9(c). Determine the overall network reliability if the individual reliabilities of the subsystems are as follows: Subsystem A = 0.95

Subsystem B = 0.97

Subsystem C = 0.92

Subsystem D = 0.94

Subsystem E = 0.90

Subsystem F = 0.88

6. A system consists of five subsystems with the following MTBFs: Subsystem A: MTBF = 10,540 hours

Subsystem B: MTBF = 16,220 hours

Subsystem C: MTBF = 9,500 hours

Subsystem D: MTBF = 12,100 hours

Subsystem E: MTBF = 3,600 hours

The five subsystems are connected in series. Determine the probability of survival for an operating period of 1000 hours.

7. A lot contains 10,000 mechanical components. A sample of 1000 component is elected from that lot. During an inspection of the sample, it is learned that the sample contains 90 defective units. Determine the upper and lower limits of sampling error.

Logistics Engineering IV (LSE400S) DISE-CPUT Tutorial 2: Reliability Page 2 of 2

Blanchard, Benjamin S. Logistics Engineering & Management: Pearson New International Edition, 6th Edition. Pearson (Intl), 10/2013. pp 76-77

8. Four basic system configurations are illustrated in Figure 19. Determine the reliability of each and rank them in order, ranking the configuration with the highest reliability fist. The individual reliability value for each of the configuration components are: Subsystem A = 0.95

Subsystem B = 0.90

Subsystem C = 0.85

Subsystem D = 0.95

Subsystem E = 0.80

9. What statistical distribution is applicable in the prediction of re liability?