A bicycle manufacturing plant is producing the first few frames for their new electric bicycle design. The first batch of 60 frames has some issues: 1/3 of the frames had a weak junction where top tube meets the seat tube. After some fine tuning, a second batch of 120 frames is made, of which 1/4 are bad, still having the weak junction. Finally, another bug is fixed and a third batch of 180 frames is made and only 1/5 of these are bad. Unfortunately, due to a clerical error, all 360 frames were combined, unlabeled, into the same shipping bin. You have access to a quick test that checks if a bike frame is defective, which is correct with probability 9/10. That is, if the bike frame is defective, the test will say it is defective with probability 9/10. If the bike frame is not defective, the test will say it is defective with probability 1/10.
A) Determine the probability that the test returns "defective," P[D].B) Determine the probability that, given the test returns "not defective," the bike frame is not bad P[Bc |Dc].
