Fair and Biased Coins

• Probability of heads on fair coin: p = 0.5 (50%)

• Biased coins do not have 50% chance of heads

• Probability of head on biased coin: p = 0.9

• Probability of tail: q = 1 - p = 1 - 0.9 = 0.1

• Whether fair or biased, the number of ways of getting 2 heads in 3 coin flips is still the same: n choose k

• The difference is in the probability of getting 2 heads in 3 coin flips