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Random Variables and Discrete Probability Distributions

Random Variables and Discrete Probability Distributions

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What is the st<strong>and</strong>ard deviation for<br />

the number of Heads for the<br />

toss of two fair coins?<br />

• we can calculate the st<strong>and</strong>ard<br />

deviation, again.<br />

�� σ2 X = [(0) 2 ·(¼) ) + (1) 2 ·(½) )<br />

+ (2) 2 ·(¼)] )] – (1)<br />

= [½ [ + 1] - 1<br />

= ½<br />

�� σX = √(½)<br />

≈ 0.707 Heads<br />

(1) 2

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