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 2 tails?

HELP Please! Thanks

What are the probabilities of coming up heads and talls???....they aren't showing up for me...

P (two tails ) = C(7,2) (3/4)^2(1/4)^5 = 189/16384 ≈ 1.15 %