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2-27. Samples of a cast aluminum part are classified on the basis of surface finish (in microinches) and edge finish. The results of 100 parts are summarized as follows: Edge Finish Excellent Good Surface Excellent 80 2 Finish Good 10 8 (a) Let A denote the event that a sample has excellent sur- face finish, and let & denote the event that a sample has excellent edge finish. Determine the number of samples in A'n B, B' and in AUB. (b) Assume that each of two samples is to be classified on the basis of surface finish, either excellent or good, and on the basis of edge finish, either excellent or good. Use a tree dia- gram to represent the possible outcomes of this experiment