Leslie M. answered 05/28/19
Certified math teacher and experienced tutor
If you are rolling a number cube, each roll is a separate and independent event. That means that to find the probability of the first event happening and the second event happening, you find the individual probabilities of each event and then multiply them.
P(roll a 4) = 1/6
P(roll an even number) = P(roll 2, 4, or 6) = 3/6
P(roll a 4, then roll an even number) = 1/6 * 3/6 = 3/36 = 1/12