Did I do this joint density problem correctly?

[miceonparade]

Homework Statement

1. Calculate Fxy(.25,.25)
2. Calculate Fx(.25)
3. Calculate Fy(.25)

Homework Equations

f(xy) = 2 (x+y) if 0$$\leq$$ x $$\leq$$ 1 and 0 $$\leq$$ y $$\leq$$ x

The Attempt at a Solution

1. without showing all of the steps of my integration (because I apparently can't work this editor too well), I get:

(2/3) * x^3 + (1/3) * x^3 0|.25

= .016



2. (2/3) * x^3 + (1/3) * x^3 0|.25

= .016



3. y + y^2 0|.25
= .3125


Did you guys come up with the same numerical answers as I did for this?

 

[LCKurtz]

.016 is approximately 1/64 so your answers are almost correct.

But why not give exact fractional values?