First let's have a look:
- nine "consists of":
9=1+8 - impossible (there is no 8, on a dice)
9=2+7 - impossible (there is no 7, on a dice)
9=3+6
9=4+5
9=5+4
9=6+3
9=7+2 - impossible (there is no 7, on a dice)
9=8+1 - impossible (there is no 8, on a dice)
the PROPER solution:
Ω - is a set of possible throwing results with two dice:
We have 6 possible outcomes in each throw, so: |Ω|=6*6=36
A -- a set of these throw results (with two dice), that the sum of the meshes is equal to 9.
We list all possibilities: (3; 6), (4; 5), (5; 4), (6; 3).
So there are 4 options,
that means: |A| = 4
therefore: |A| 4
P(A) = --------- = -----
| Ω | 36
It is 0% of the probability that the first number will be 2, because, as listed before the second number should be 7 (2+7)=9, and there is NO 7 on a dice.