We flip a fair coin 10 times. What is the probability that we get heads in at least 8 of the 10 flips?
+1223 total possible sequences of flips: 2^10 = 1024 (there are only two choices for each flip, heads or tails, for ten flips)
8 heads: 10 choose 8 = 45 (the number of ways to arrange the sequence HHHHHHHHTT)
9 heads: 10 choose 9 = 10
10 heads: 10 choose 10 = 1
total probability: (45 + 10 + 1)/1024 = 56/1024 = 7/128
