1 .
A bowl contains 5 blue balls and 4 red balls. We choose 2 balls uniformly at random. Define the
events
- A = "both balls are red",
- B = "both balls have the same color".
(a)
$\frac{{5 \choose 2} + {4 \choose 2}}{{4 \choose 2}}$
(b)
$\frac{{4 \choose 2}}{{5 \choose 2}{4 \choose 2}}$
(c)
$\frac{{4 \choose 2}}{{5 \choose 2} + {4 \choose 2}}$
(d)
$\frac{{4 \choose 2}}{{9 \choose 2}}$