You're doing good. Now you just need to subtract off P(A and B).
The ones who are greater than 9 AND have an even sum. In other words, the pair who sum to 10 and 12.
I'm having trouble with this probability question.
"Find the probability of rolling an even sum or a sum greater than nine when a pair of dice is rolled."
So P(A)= even sum when dice rolled
(1,1) (1,3) (1,5) (2,2) (2,4) (2,6) (3,3) (3,5) (4,4) (4,6) (5,5) (6,6)
P(B)= sum greater than nine when dice rolled
(4,6) (5,5) (5,6) (6,6)
P(A or B) (A and B)
..and now I'm stuck, I don't know if I'm even doing it right.
help?
Hello, Hypertension!
You're using the wrong denominator.
When a pair of dice is rolled, there are: . outcomes.
: Even sum is rolled: .(1,1) (1,3) (1,5) (2,2) (2,4) (2,6) (3,3) (3,5) (4,4) (4,6) (5,5) (6,6)Find the probability of rolling an even sum or a sum greater than nine
when a pair of dice is rolled.
. .
: Sum greater than nine is rolled: .(4,6) (5,5) (5,6) (6,6)
. .
: Sum is even and greater than nine: .(4,6) (5,5) (6,6)
. . It's the overlap of and : .
Therefore: .
ok, so I include the rolled numbers too?
so technically it would be,
P(A)= sum of even numbers: .(1,1) (1,3) (1,5) (2,2) (2,4) (2,6) (3,3) (3,5) (4,4) (4,6) (5,5) (6,6) (3,1) (5,1) (4,2) (6,2) (5,3) (6,4)
P(B)= sum of numbers greater than nine: (4,6) (5,5) (5,6) (6,6) (6,4) (6,5)
Then P(A and B) =
So, P(A or B)=