math1
posted by pankaj .
(ii) A factory has two machines. Past records show that the first machine produces 40% of output and the second machine produces 60% of output. Further 4% and 2% of the products produced by the first machine and the second machine were defectives. If a defective item is drawn at random, what is the probability that the defective item was produced by the first machine or second machine?

say we make 1000 total
400 from #1, 16 defective
600 from #2, 12 defective
Tat is a total of 28 defective
16/28 = .57 from #1
12/28 = .43 from #2