Answer
$\frac{2}{3}$
Work Step by Step
P(event)=$\frac{numberoffavorableoutcomes}{numberofpossibleoutcomes}$
There are 6 possible outcomes. There are 4 numbers which are less than 5(1,2,3,4) so 4 is the number of favorable outcomes.
P(event)=$\frac{numberoffavorableoutcomes}{numberofpossibleoutcomes}$
P(less than 5)=$\frac{4}{6}$ -simplify-
P(less than 5)=$\frac{2}{3}$