Question

Two coin are tossed. Let T be the number of tails that occur. Determine the values of the random varibale T.

Answer 1

When 2 coins are tossed, the sample space $S$ is,

$S=\{HH,HT,TH,TT\}$.

Let the random variable $T$ denote the number of tails that occur. $T$ may take on the values, $0,1,2$. That is, $t=0,1,2.$   

 So,

probability of getting 0 tails is ${1\over4}$

probability of getting 1 tail is ${1\over4}+{1\over4}={2\over4}={1\over2}$

probability of getting 2 tails is ${1\over4}$.