What is the probability of getting zero heads in two flips of a fair coin?

• A. 0
• B. 1/2
• C. 1/4
• D. 3/4

Answer: (C)

When you want zero heads in two coin flips, you’re looking for both flips to come up tails. With a fair coin, each flip has a 1/2 chance of tails, and the flips don’t affect each other, so you multiply: 1/2 × 1/2 = 1/4.

Another way to see it is to list the four equally likely outcomes of two flips: HH, HT, TH, TT. Only one of these outcomes has zero heads (both tails), so the probability is 1 out of 4, or 1/4.

The other numbers correspond to different events: zero is impossible for two flips, 1/2 would be the chance of tails on a single flip, and 3/4 is the chance of getting at least one head in two flips.