ECON 250 Midterm: ECON 250 Pastmidterm2 test2W07sol comb
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ECON 250 Full Course Notes
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The number of cars sold per day in dan"s used car superstore is de ned by the following probability distribution. x. 0. 10 (a) construct f (x), the cumulative probability distribution function for x. (b) calculate p (x > 3) (c) calculate p (x 4) 1. 00 (b) p (x > 3) = 0. 1 + 0. 1 = 0. 2 (c) p (x 4) = 0. 10 + 0. 20 + 0. 30 + 0. 20 + 0. 10 = 0. 9 or. P (x 4) = 1 p (x = 5) = 1 0. 1 = 0. 9. Suppose x is a discrete random variable that can take 3 di erent values. Its probability distribution is x p (x = x) 0. 5 (a) calculate e[x]. (b) calculate v [x]. (c) calculate e[x 2]. (d) calculate e[2 + 3x]. (e) calculate v [2 + 3x]. Answers (a) e[x] = px xp (x = x) = 2 0. 2 + 3 0. 3 + 5 0. 5 = 3. 8 (b)
