Operations Management: An Integrated Approach, 5th Edition

Solved Problems

(See student companion site for Excel template.)

• Problem 1

An office security system at Delco, Inc. has two component parts, both of which must work for the system to function. Part 1 has a reliability of 80 percent, and part 2 has a reliability of 98 percent. Compute the reliability of the system.

• Before You Begin:

Before you begin solving reliability problems, it is best to first draw a diagram of the components. Remember that the system of components is drawn in series, except when there is redundancy built into the system through a backup component. In that case, the backup component is drawn in parallel. Always read the problem carefully to determine whether redundancy is built into the system.

• Solution

The reliability of the system is

R_s = R₁ × R₂

R_s = (0.80)(0.98) = 0.784

• Problem 2

Delco, Inc., from Problem 1, is not happy with the reliability of its security system and has decided to improve it. The company will add a backup component to part 1 of its security system. The backup component will also have a reliability of 0.80. What is the reliability of the improved security system?

• Before You Begin:

Notice that in this problem there is redundancy in the form of a backup component for part 1. This means that when drawing the diagram you should place the two components for part 1 in parallel. Proceed by computing the reliability for part 1 and then ...