Finding the PDF and CDF of a given function Z = X/Y

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
2 replies · 2K views
whitejac
Messages
169
Reaction score
0

Homework Statement


Given a Uniform Distribution (0,1) and Z = X/Y
Find F(z) and f(z)

Homework Equations

The Attempt at a Solution


So I'm just trying to make sure i have the range correct on this one... I'm honestly lost from beginning to end with it.
R(z) = {0,∞} because as y is very small, Z becomes very big.
After that, I'm not quite sure though because that would mean that P(z) would be 1 for z > ∞, and that doesn't make much sense...
 
Physics news on Phys.org
whitejac said:

Homework Statement


Given a Uniform Distribution (0,1) and Z = X/Y
Find F(z) and f(z)

Homework Equations

The Attempt at a Solution


So I'm just trying to make sure i have the range correct on this one... I'm honestly lost from beginning to end with it.
R(z) = {0,∞} because as y is very small, Z becomes very big.
After that, I'm not quite sure though because that would mean that P(z) would be 1 for z > ∞, and that doesn't make much sense...
Did you mean
$$\lim_{z \to \infty} P(Z≤z) = 1?$$ If so, what's the problem with that?
 
whitejac said:

Homework Statement


Given a Uniform Distribution (0,1) and Z = X/Y
Find F(z) and f(z)

Apparently you haven't given us everything you know. Are X and Y both uniform distributions on (0,1)? Are they given to be independent?

Homework Equations

The Attempt at a Solution


So I'm just trying to make sure i have the range correct on this one... I'm honestly lost from beginning to end with it.
R(z) = {0,∞} because as y is very small, Z becomes very big.

Best not to use set notation for intervals. I suppose you mean ##R(z) = (0,\infty)##, which would be the correct range.

After that, I'm not quite sure though because that would mean that P(z) would be 1 for z > ∞, and that doesn't make much sense...

What does P(z) mean? I agree, ##z>\infty## makes no sense. You would expect the cumulative distribution function to approach 1 as ##z\to\infty##.