If a dice is rolled three times, what is the probability of rolling a 3 at least once?
First,find the probability that no six occurs in 3 throws,which will be equal to $\displaystyle =(\frac{5}{6})(\frac{5}{6})(\frac{5}{6})=(\frac{5} {6})^3$
Therefore the probability that at least one six occurs will be
$\displaystyle
=1-(\frac{5}{6})^3=\frac{91}{216}
$