# Binomial Disbribution Conditional Probability

What is the probability of tossing $k$ heads in $n$ trials conditional that in first $t$ attempts there was one head? And the coin is fair.

Is it $\mathbb{P}(k-1,n-t)$?

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 Please, anyone? – Norman Dec 11 '12 at 11:10 I think here it could be more motivating to explain the notation, say what you tried and where you're stuck. – Learner Dec 11 '12 at 12:51 It all depends on what the (non-standard) notation means. It it means $\dbinom{n-t}{k-1}(1/2)^{n-t}$ then yes. – André Nicolas Dec 11 '12 at 17:37