Notice that there are two ways in which the toss could result in a combination of heads and tailscoin 1 heads and coin 2 tails, or coin 1 tails and coin 2 heads. The probability of each headstails outcome is one chance in four, or 25%. Since there are two headstails combinations, the probability of getting headstails is 50%. The ratio of all four possible outcomes is 25% headsheads, 50% headstails, and 25% tailstails, or 1:2:1

Tossing two coins at once can result in four possible outcomes.  