Find the Probability of Joint PDF X and Y with Easy Calculation

[sjaguar13]

Given this joint PDF of X and Y:

X\Y	1	2
0 	0.1	0.3
1	0.05	0.1
2	0.2	0.25

So:
P(X = 1| X+Y=2) = 1/2?
P(X <= 1 and Y <= 2) = 1/3?

 

[sjaguar13]

...Anyone?

 

[HallsofIvy]

Given this joint PDF of X and Y:

X\Y	1	2
0 	0.1	0.3
1	0.05	0.1
2	0.2	0.25

So:
P(X = 1| X+Y=2) = 1/2?
P(X <= 1 and Y <= 2) = 1/3?

I don't get either of those. How did you get those answers?