Two fair coins are tossed simultaneously. Given that at least one head appears, what is the probability that both coins show heads?
1/3
When two coins are tossed, the sample space is \(\{HH, HT, TH, TT\}\), each equally likely.
The event "at least one head" excludes only TT, leaving the reduced sample space \(\{HH, HT, TH\}\) with 3 outcomes.
Among these, only \(HH\) has both coins showing heads, so the required conditional probability is \(\frac{1}{3}\).
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