2. A coin is tossed twice, what is the probability that atleast one tail occurs?
Sample space when a coin is tossed twice, S = {HH, HT, TH, TT}
[Note: A coin tossed twice is same as two coins tossed at once]
Number of possible outcomes n(S) = 4
Let E be the event of getting at least one tail = {HT, TH, TT}
n(E) = 3
= 0.75