Consider two machines, A and B, each producing the same items. Each machine produces large number of these items every day. However, production per day from machine B, being newer, is twice that of A. further the rate of defectives is 1% for B and 2% for A. the daily output of the machines is combined and then a random sample of size 12 taken. Find the probability that the sample contains 2 defective items. What assumptions are you making?