Question

In tossing three fair coins together what is the probability of getting atmost two heads

Answer 1

In tossing three fair coins together, the sample space is given by:
$S=\{HHH,HHT,HTH,THH,HTT,THT,TTH,TTT\}$
$\therefore n\left(S\right)=8$
Let $D$ be the event of getting atmost two heads
$A=\{HHT,HHT,HTH,THH,HTT,THT,TTH,TTT\}\therefore n\left(D\right)=7$
$\therefore P\left(D\right)=\frac{n\left(D\right)}{n\left(S\right)}=\frac{7}{8}$