What is the theoretical probability of tossing two fair coins and having one land on heads an the other one lands on tails?

Answer 1

Depending on the specifications, it could be 1/4 (25%) or 1/2 (50%). If you specify that Coin A must be heads and Coin B is tails, then it is 25%: Because you have 1/2 chance for each coin, you multiply these chances together : (1/2) x (1/2) = 1/4

However if you just want 'one of the coins' to be heads, and 'the other coin' to be tails, then it is 1/2 (50%). Here are the 4 possible outcomes:

1. Both A & B are heads
2. Both A & B are tails
3. A is heads, B is tails
4. A is tails, B is heads.

So for outcomes # 3 & 4 meets our criteria. This is 2 out of the 4 possible, or 2/4 = 1/2 or 50%.