# Math Help - Finding the pmf from the distribution function

1. ## Finding the pmf from the distribution function

No idea how to do part (a). Can someone please help me? Thanks!

2. Originally Posted by cirrus74

No idea how to do part (a). Can someone please help me? Thanks!
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