An unbiased die is thrown. What is the probability of getting:
a number 3 or 4.

In a single throw of a die we can get any one of the six numbers 1, 2, ..., 6 marked on its six faces. Therefore, the total number of elementary events associated with the random experiment of throwing a die is 6.
Let A denote the event "Getting 3 or 4"
Clearly, A occurs when we get either 3 or 4 as an outcome.
$\therefore$ Favourable number of elementary events = 2.
Hence, $P(A)=\frac{2}{6}=\frac{1}{3}$