Question: 2015 Fall Final - 12
A bowl contains 5 red balls and 7 blue balls. We choose a uniformly random subset of 3 balls. Define the event
- A = "exactly 2 of the chosen balls are red".
(a)
$\frac{{5 \choose 2} \cdot 7}{{12 \choose 3}}$
(b)
$\frac{5 \cdot {7 \choose 2}}{{12 \choose 3}}$
(c)
$\frac{{5 \choose 2}}{{12 \choose 3}}$
(d)
$\frac{{7 \choose 2}}{{12 \choose 3}}$