Stat 21 Quiz _3 Key

Ifthesecondrollislessthanfirstsheloses

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Unformatted text preview: or X. B) Evaluate: i) P(X ≥ 1.8) = 0 ii) P(X ≤ ‐2.3) = 0 iii) P(X ≥ 0.5) = 0.25 D) Calculate: i) E(X) = -0.05 X ‐1 0 1 E(x) = Var(X) = P(X=x) 0.3 0.45 0.25 ‐0.05 0.5475 ii) Var(X) = 0.5475 x ‐ u ‐0.95 0.05 1.05 (x ‐ u)^2 0.9025 0.0025 1.1025 (x ‐ u)^2 * P(X=x) 0.27075 0.001125 0.275625 Stat 21 Quiz #3 October 12, 2011 2. Francie is playing a dice game with another GSI. In the game, she rolls a dice two times. If the second roll is bigger than the first, she wins $2. If the second roll is less than first, she loses $1. If the second roll is equal to the first roll she wins no money, but does not lose money. A) Create a probability model for the amount of money that Francie wins in the dice game. x P(x) Wins $2 15/36 = .4167 Loses $1 15/36 = .4167 No wins or losses (if two rolls are the same) 6/36 = .167 B) Draw a cumulative distribution function (cdf) for the amount of money that Francie wins in the dice game. C) How much money can Francie expect to win o...
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