A system of computer servers has three parts with reliabilities of 0.89,0.79,and 0.79.In order to improve the reliability,Parts 2 and 3 have backups with corresponding of reliability of 0.95 and 0.96.Compute the composite reliability of the server system.
A)0.78
B)0.68
C)0.87
D)0.44

Question

Quizplus · Accepted Answer

The composite reliability of the system can be calculated as:

R_system = R1 x (R2 x R3_backup)

where R1 is the reliability of part 1, R2 is the reliability of part 2, and R3 is the reliability of part 3.

So,

R_system = 0.89 x (0.79 x 0.96 x 0.95)  [Note that we need to use the backup reliability of part 3 here]

R_system = 0.68

Therefore, the best choice is (C) 0.87, which is not an option.

A System of Computer Servers Has Three Parts with Reliabilities