Managing for Quality and Performance Excellence 10th Edition by James Evans ,William Lindsay

Exercise 68

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Magnaplex, Inc. has a complex manufacturing process, with three operations that are performed in series. Because of the nature of the process, machines frequently fall out of adjustment and must be repaired. To keep the system going, two identical machines are used at each stage; thus, if one fails, the other can be used while the first is repaired (see accompanying figure).
Production System

The reliabilities of the machines are as follows:

a. Analyze the system reliability, assuming only one machine at each stage (all the backup machines are out of operation).
b. How much is the reliability improved by having two machines at each stage?