The sample space of the experiment is  S = {HH, HT, TH, TT} If X denotes the number of heads obtained, then X is a random variable and for
each outcome, its value is as given below :
X(HH) = 2, X (HT) = 1, X (TH) = 1, X (TT) = 0 More than  one random variables can be defined on the same sample space For
example, let Y denote the number of heads minus the number of tails for each outcome
of the above sample space S