Question

You are rolling two dice at the same time. What is the probability of rolling a sum of 5 or 9?

Answer 1

do you know either of the probabilities? if so, you add them together

Answer 2

yes i do ..im just making sure i got them right

Answer 3

it is easy enough to remember, but we can simply list the ways to roll a total of five
(1,4), (2,3), (3,2), (4,1) so there are 4 ways out of a total of 36 and therefore the probability you get a 5 is
\[\frac{4}{36}\]

Answer 4

possible ways of getting a 5 are 2 and 3, 1 and 4, 3 and 2 and 4 and 1.

Answer 5

similarly there are 4 ways to roll a 9, namely
(3,6), (4,5), (5,4), (6,3)
and again the probability is
\[\frac{4}{36}\]
now since you cannot roll both a 9 AND a 5, the intersection is empty, and so your OR statement becomes an addition
\[\frac{4}{36}+\frac{4}{36}\]

Answer 6

oh ok i get it