Question: 2013 Fall Midterm - 15
If you flip a fair coin 4 times, what is the probability that the coin comes up heads exactly twice?
(a)
${{4}\choose{2}}/2^{4}$
(b)
$1/{{4}\choose{2}}$
(c)
$2^{4}/{{4}\choose{2}}$
(d)
$2/2^{4}$