A discrete uniform random variable,X, has PMF of the form

px(k) = {(1/b-a+1), k =a,a+1....b,

0 otherwise}

whereaandbare two integers witha<b

how do i sketch the PMF of X?

how do i work out E[X]?

Sorry about lack of LaTex Math

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- Oct 13th 2009, 10:18 AMsirellwoodDiscrete Uniform Random Variable
A discrete uniform random variable,

**X**, has PMF of the form

px(k) = {(1/*b*-*a*+1), k =*a*,*a*+1....*b*,

0 otherwise}

where*a*and*b*are two integers with*a*<*b*

how do i sketch the PMF of X?

how do i work out E[X]?

Sorry about lack of LaTex Math - Oct 13th 2009, 02:50 PMmatheagle
You're placing equal probability on the numbers a, a+1,...,b.

The mean is the 'midpoint'.

Just add the integers from a to b and divide by the number of terms, b-a+1. - Oct 14th 2009, 02:37 PMsirellwood
im sorry, i dont understand what you are saying?

- Oct 14th 2009, 03:06 PMsirellwood
am i not right in thinking that E[X] =$\displaystyle \frac{1}{b-a+1}$ x $\displaystyle \frac{b+a}{2}$?

as $\displaystyle \frac{b+a}{2}$ would be moo of all the values k will take and $\displaystyle \frac{1}{b-a+1}$ is the probability of all these values?