# Homework Help: Cumulative Distribution Function problem

1. Oct 19, 2011

### l46kok

1. The problem statement, all variables and given/known data
Let the independent random variables X1,X2,X3 have the same cdf F(x). Let Y be the middle value of X1,X2,X3. Determine the cdf of Y.

2. Relevant equations

F(x) = P(X<=x) = ∫-inf to x f(y)dy

3. The attempt at a solution

I don't understand the question, what does it exactly mean when Y is the middle value of X1,X2,X3? I'm not exactly sure where to start. Can somebody help?

2. Oct 19, 2011

### HallsofIvy

If one sample is $X_1= -5$, $X_2= 3000$, $X_3= 500$, then Y is the "middle value", 500. 500 is the "middle value" because -5< 500< 3000.

3. Oct 19, 2011

### l46kok

Oh.. Ok

I'm still a bit lost on how to tackle this problem..