Question

Three coins are tossed simultaneously. Find the probability that at least two heads turn up.

Answer 1

Three coins are tossed simultaneously:
$S=\{HHH,HHT,HTH,TTT,THT,TTH,HTT,THH\}$
$\therefore n\left(S\right)=8$
Let $A$ be an event that at least two heads turn up.
$A=\{HHH,HHT,HTH,THH\}$
$\therefore n\left(A\right)=4$
$\therefore P\left(A\right)=\frac{n\left(A\right)}{n\left(S\right)}$
$=\frac{4}{8}$
$=\frac{1}{2}$.