A coin is tossed twice, what is the probability that atleast one tail occurs?

Explanation

Required sample space = S
= {HH,HT,TH,TT}.
Let A: ‘at least one tail occurs’A = {HT,TH,TT}
We have, n(A) = 3, n(S) = 4 = `2^2`

Required probability = P(A) = `(n(A))/(n(s))` = `3/4`