STATISTC 515 Midterm: STATS 515 UMass Amherst S515.Spring17.Midterm1
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Instruction: notes, calculators, and other electronics are not allowed, show all your work. You need to fully justify all of your answers. A correct answer with insu cient justi cation may receive no credit: a formula sheet is provided in the last page, you have 2 hours to complete the exam. 2: a pair of dice are rolled. Each die has the shape of a polyhedron with four sides numbered. List the sample points in a and b. (c) (9 points) find the following probabilities: (i) p (a b). (ii) p (a b). (iii) p (a|b): (a) (6 points) three companies produce colored balls. 20% of balls from company a are red, 30% of balls from company b are red, and 70% of balls from company c are red. You buy a ball from a store (which buys its balls with equal probability from a, b, or: and observe that it is not red.
