# Math Help - what is the meaning of

1. ## what is the meaning of

$f_Y(y)$

f means density function what are Y and y
?

2. Originally Posted by transgalactic
$f_Y(y)$

f means density function what are Y and y
?
Y is the random variable. And since f is a function, .....

3. what is y then?

4. Originally Posted by transgalactic
what is y then?
Well, if I have a function g(x), say, what is x ....? Perhaps you need to go back to revise your pre-calculus work on functions.

5. Originally Posted by transgalactic
$f_Y(y)$

f means density function what are Y and y
?
It is the density of the RV Y evaluated at y.

CB

6. Originally Posted by CaptainBlack
It is the density of the RV Y evaluated at y.

CB
i see your words are much closer to what i am looking for

can you say what is RV
why Y evaluated by y

can you give a simple example so it will be clear

7. Originally Posted by transgalactic
i see your words are much closer to what i am looking for

can you say what is RV
why Y evaluated by y

can you give a simple example so it will be clear
RV means a random vairable

Y being evaluated at y means you are finding the pdf(probability density function) of the random variable!

8. ## meaning of...

life?
well that's 42.