EGR 252 - 2 1

Serial and Parallel Systems

• For increased safety and reliability, systems are often designed with redundancies. A typical system might look like the following:

0.95 0.9

0.88

0.85

0.97

A B

C

D

E

EGR 252 - 2 2

Serial and Parallel Systems

• What is the probability that:– Segment 1 works?

– Segment 2 works?

– The entire system works?

0.95 0.9

0.88

0.85

0.97

A B

C

D

E

12

EGR 252 - 2 3

Conditional Probability

• If segment 2 works, what is the probability that component C does not work?

P(B|A) = P(B ∩ A) / P(A)

1

2

0.95 0.9

0.88

0.85

0.97

A B

C

D

E

EGR 252 - 2 4

Conditional Probability

• If the system works, what is the probability that component D does not work?

0.95 0.9

0.88

0.85

0.97

A B

C

D

E

EGR 252 - 2 5

Your turn …

• Problem 2.79, page 65