# Probability Question about CDFs

Just wondering if someone could help me out on a problem. i mean PDFs, not CDFs in the title. Soz

<_ means greater and equal to

Well, if we give Z to be a random varible with a pdf of:

pdf of Z = (5/2)*z^3 if -1<_ z _> 1
0 otherwise

Suppose that X = 2-Z^2

What is the pdf of X?

## Answers and Replies

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lanedance
Homework Helper
what do you think? the idea is to have a go and get some help with your work...

well if i first find the CDF of FX(x) then um, try plugging it in to find the probablility of y<_y?

Homework Helper
The notation $$-1 \le z \ge 1$$ doesn't make any sense. do you mean $$-1 \le z \le 1$$?

yes i do mean $$-1 \le z \le 1$$

can u help me on the question?

lanedance
Homework Helper
well if i first find the CDF of FX(x) then um, try plugging it in to find the probablility of y<_y?
ok so what is y & what do you plan to "plug-in"?

Based on the question, I would use the known CDF/PDF of Z and try & use it to calculate that of X