I have seen some places saying that the sum of $2$ dice being thrown being less than $5$ can occur for the cases
$$(1,1),(2,2),(2,1),(3,1),$$
giving a probability of $\frac4{36}$ for the event.
However, I have also seen people counting the numbers twice, as there are two different ways to throw the dice, giving the cases
$$(1,1),(1,1),(2,2),(2,2),(2,1),(1,2),(3,1),(1,3),$$
and a probability of $\frac8{36}$.
Which way is correct?
Best Answer
Neither is correct. The second approach is the correct one – you list all the ordered possibilities. Nevertheless, you have listed $(1,1)$ and $(2,2)$ twice.