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

H Harsh Kankaria

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]

$\therefore$ Number of possible outcomes n(S) = 4

Let E be the event of getting at least one tail = {HT, TH, TT}

$\therefore$ n(E) = 3

$\therefore$ $\dpi{100} P(E) = \frac{n(E)}{n(S)}$  $= \frac{3}{4}$

= 0.75

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