Two methods A and B are available for teaching a certain industrial skill. The success rate is 80% for A and 90 % for B. However, B is more expensive and hence, is used only 30% of the time (A is used for the other 70%). (Bayes) A) If a person is taught the skill by any of these two methods, what is the probability of success? B) A worker is taught the skill by one of the methods but fails (not succeeds) to learn it correctly. What is the probability that he was taught by method A?