A coin is tossed twice. If the outcome is at most one tail, what is the probability that both head and tail have appeared?


A coin has 2 sides and its sample space S={H,T}


The total number of outcomes = 2.


A coin is tossed twice.


Let P(A) be the probability of getting at most 1 tail.


The sample space of A = {(H,H),(H,T),(T,H)}


Let P(B) be the probability of getting a head.


The sample space of B = {H}



The probability of getting at most one tail and a head




Tip – By conditional probability, where is the probability of occurrence of the event A given that B has already occurred.


The probability that both head and tail have appeared:






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