Question

A coin is tossed 10 times. What is the probability that at least 8 heads appear?

Answer 1

so you want 8 heads, 9 heads or 10 heads

prob = C(10,8) (1/2)^10 + C(10,9) (1/2)^10 + C(10,10) (1/2)^10
= (1/2)^10 (45 + 9 + 1)
= 55 (1/2)^10 = 55/1024 or appr .0537