STAT 400 Study Guide - Final Guide: Random Variable, Rule Of Inference, Probability Mass Function

• School: University of Maryland
• Department: Statistics and Probability
• Course: STAT 400
• Professor: Tim Pilachowski

Document Summary

Stat 400, section 3. 6b change of variables: expected value and variance notes prepared by tim pilachowski. Specifically, do you remember graphing functions, and using shifts and translations? xf. More recently, in calculus, you saw integration by substitution and the change of limits rule. Each of these is an example of change of variables , an algebraic rule that transforms one variable or function into another which either more useful or more informative. Your text covers this in a subsection of 3. 3 titled the expected value of a function . Today"s lecture is a slightly more thorough exploration of this topic. The text"s example 3. 21 transforms x = number of books sold to y = revenue from selling x books. Example 3. 22 transforms x = number of cylinders in an engine to y = cost to diagnose an engine with x cylinders. Let random variable y = 3x + 10, where the probability distribution for random variable x is: x.