COMM 291 Lecture Notes - Lecture 11: Household Income, Central Limit Theorem, Binomial Distribution
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Commerce 291 lecture notes jonathan berkowitz (copyright, 2014) In lecture 9 (textbook: chapter 9) we discussed a set of rules for computing the mean, the variance and the standard deviation of combinations of random variables. Now we combine these rules with the normal distribution (chapter 9) and learn applications of the normal distribution and why it is so often. - if x and y are random variables each with a normal distribution, x + y also has a normal distribution; that is, adding normals give a normal. For example, if x is n( x, x), y is n( y, y), and x and y are independent, then: X+y is n((cid:3025)+(cid:3026), (cid:3025)(cid:2870)+(cid:3026)(cid:2870)), and x-y is n((cid:3025) (cid:3026), (cid:3025)(cid:2870)+(cid:3026)(cid:2870)). Fred and barney are playing in a golf tournament. Record-keeping from previous years show that fred"s scores are normally distributed with mean 110 and standard deviation. 10, and that barney"s scores are normally distributed with mean 100 and standard deviation 8.