George flips an unfair coin 7 times. The coin has a 1/4 probability of coming up heads and a 3/4 probability of coming up tails. What is the probability that he flips exactly 3 tails?
The probability is given by :
C(7,3) (1/4)^4 (3/4)^3 = 945 / 16384 ≈ .0577
