Suppose I flip two coins without letting you see the outcome, and I tell you that at least one of the coins came up heads. What is the probability that the other coin is also heads?

Through cond prob. I think the answer is 1/4, but others are saying its 1/3. There are 4 possible combinations, and knowing that at least one coin turned up heads doesnt change the probability of getting HH in flipping 2 coins.

we cant just eliminate TT from the equation bc before you flipped the coins, TT has 1/4 chance of turning up.

But if you said right from the start that the coins are somehow biased that at least 1 coin will always turned up heads, then i would agree that the probability of getting HH is 1/3.

otherwise if getting HH, HT, TH or TT have equal chances, then it should be 1/4.

Thoughts?