SOLUTION: An electronic assembly consists of 2 sub systems A and B. from the previous testing procedures the following probabilities are known: P(A fails)=0.2 P(B fails alone)=0.15 P(A an

Algebra ->  Probability-and-statistics -> SOLUTION: An electronic assembly consists of 2 sub systems A and B. from the previous testing procedures the following probabilities are known: P(A fails)=0.2 P(B fails alone)=0.15 P(A an      Log On


   



Question 118388: An electronic assembly consists of 2 sub systems A and B. from the previous testing procedures the following probabilities are known:
P(A fails)=0.2
P(B fails alone)=0.15
P(A and B fails)=0.15
evaluate P(A fails given B fails) {conditional probability}
and
P(A fails alone).

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
P(A fails)=0.2
P(B fails alone)=0.15
P(A and B fails)=0.15
evaluate P(A fails given B fails) ------------------
and
P(A fails alone).
--------
An electronic assembly consists of 2 sub systems A and B. from the previous testing procedures the following probabilities are known:
P(A fails)=0.2
P(B fails alone)=0.15
P(A and B fails)=0.15
evaluate P(A fails given B fails) {conditional probability}
and
P(A fails alone).
-------------------
P(A fails | B fails) = [P(A fails and B fails)]/[P(B fails] = 0.15/P(B fails)
but P(B fails) = P(B fails alone) + P(B fails and A fails) = 0.15 + 0.15 = 0.30
So P(A fails|B fails) = 0.15/0.30 = 1/2
-------------------------
P(A fails alone) = P(A fails and B does not)
=P(B does not fail|A fails)*P(A fails)
=(1-P(A and B fails))*0.2
=(1-0.15)*0.2
=(0.85)*0.2
= 0.17
=================
Cheers,
Stan H.