Let
us try to answer this question by taking up a random experiment in which the outcomes
are equally likely to occur Consider the experiment of tossing three fair coins The sample space of the
experiment is
S = {HHH, HHT, HTH, THH, HTT, THT, TTH, TTT}
Chapter 13
PROBABILITY
Pierre de Fermat
(1601-1665)
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not to be republished
 532
MATHEMATICS
Since the coins are fair, we can assign the probability  1
8   to each sample point Let
E be the event ‘at least two heads appear’ and  F be the event ‘first coin shows tail’