# Thread: Finding the pmf from the distribution function

1. ## Finding the pmf from the distribution function

2. Originally Posted by cirrus74

I think we will have to assume that the possible values of $x$ are integers, then:

(a) well obviously we have:

$p_X(x)=0,\ x<-1$

and

$p_X(x)=0,\ x \ge 1$,

so that leaves only $p_X(-1)$ and $p_X(0)$ to be determined, can you do that?

RonL

3. Well actually, the answer that was given to us was:

But I don't know how they got it?

4. Originally Posted by cirrus74
Well actually, the answer that was given to us was:

But I don't know how they got it?
When $F$ jumps by $d_i$ at $x_i$, then $p(x_i)=d_i$

RonL