Finite Chapter 8.1

Finite Chapter 8.1 - Math 120 SP08 SBrodnick 8.1: Random...

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Math 120 SP08 SBrodnick 1 1 Chapter 8 : Random Variables & Statistics 8.1 : Random Variables & Distributions 2 * Random Variable X : rule that maps outcomes of an experiment to a number or value (like a function) * Can compute prob. of each value of X and make prob. distribution * Recall : * Estimated prob. (data) * Theoretical prob. (intuition) 3 Examples : 1. X: # of times H comes up when 2 dist. coins are tossed Outcomes Value of X Probability distribution: Value of X Probability HH HT TH TT 2 0 1 2 1 1 0 1/4 2/4 1/2 1/4 P(X ≥ 1) = ½ + ¼ = ¾ = P(1) + P(2) 4 2.X: largest # of consecutive times tails comes up (in a row) when a coin is tossed 3 times Outcomes Value of X Probability distribution: Value of X Probability P(X < 2) HHH HHT HTH THH TTH THT HTT TTT 0 0 1 2 3 1 1 1 1/8 4/8 1/2 2/8 2 1 2 3 1/8 1/4 = P(0) + P(1) = 1/8 + 4/8 = 5/8 5 3.X: sum when two indist . dice are rolled

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This note was uploaded on 04/07/2008 for the course MAT 120 taught by Professor Brodnick during the Spring '08 term at Illinois State.

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Finite Chapter 8.1 - Math 120 SP08 SBrodnick 8.1: Random...

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