Probability of part A defective:- 9/100=0.09
Probability of part B is defective:- 0.05
....as we know that article is the combination of both part A and Part B.....
Assembled article would be defective in following cases...
1.part A is defective not B:- .09*0.95
2.part B is defective not A:- .05*0.91
3. Both are defective..:- .05*.09
sum all the cases
:-