Let
Y1
and
Y2
have joint density function

e-
y1
+y2),
e
y1
0,
y2
0,
>
>
=
f
y1, y2)

0,
elsewhere.
a
What is P
(Y1
1,
Y2
5)?
<
>
+
b
What is P
(Y1
Y2
3)?