next up previous index
Next: Properties of Expectation 11/6 Up: Expectation and Variance 11/6 Previous: Expectation and Variance 11/6

   
Discrete Random Variable 11/6

The Expected value of a random variable X with probability mass m is defined as:

\begin{displaymath}E[X]=\sum_{x:m(x)>0}x . m(x)\end{displaymath}

Example of the dice game:
Say you lose the points marked for an odd number, win the points marked for an even one. What is your expected gain?

\begin{displaymath}E[X]=\frac{1}{6}\times(-1)+ \frac{1}{6}\times(+2)+
\frac{1}{...
...6}\times(+4)+ \frac{1}{6}\times(-5)
+ \frac{1}{6}\times(+6)=0.5\end{displaymath}



 

Susan Holmes
1998-12-07