I'm finding it difficult to understand the explanation for my problem's solution, I would like to post it here so maybe one of you could enlight my understanding.
Just to clarify, I'm studying for a Probability test and I'm stuck at this exercise (and I'm pretty bad with functions of R.V.s), so the Homework tag is just to let it clear that I'm looking for something for dummies :/
Problem is: Given two i.i.d., exponential with $\lambda = 4$ R.V.s, X and Y, find the p.d.f. of $Z = \frac{X}{X+Y}$
Thanks in advance.