Question

P(rollinga 3 or 5 on a die)'

Answer 1

We have to calculate the probability of rolling a 3 or a 5 in a dice.

To do so, we assume a fair dice (all the faces have the same probabiity).

Then, the probability can be calculated as the quotient of the number of "success" events (2 events: "rolling a 2" and "rolling a 5") and the number of possible outcomes (6 events, rolling a 1, 2, 3, 4, 5 or 6).

Then, the probability is:

$P(3\text{ or }5)=\frac{2}{6}=\frac{1}{3}\approx0.33$

The probability of rolling a 3 or a 5 is 1/3 or 0.33.