System and Component Probability Calculations

[kasse]

The numbers represent the probability that each component works.

a) What's the probability that the entire system works?
b) Given that the system works, what's the probability that the component A is not working?

a) P=.75112, easy
b) Don't know what to do here...

 

[statdad]

Since there is no component A in the diagram, I'd say you can't answer the second question.
If you were asking this: Given the system works, what is the probability 1
is not working, think this way:

If the system is operating, you know that
* 3, 4 and 5 are all operating
and
* 1 is not operating, status of 2 is unimportant

what can you do with this?