|
1 |
2 |
3 |
4 |
5 |
6 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
Row is the first die; column is the second die. The cells are the sums of the dice.
Second die=2 or 3 are columns 2 and 3. In those columns, 7 appears twice and 9 once.
So we need the total number of possibilities where the second die=2 or 3. There are 12 possibilities, and 3 of these gives us a sum of 7 or 9, so the probability is 3/12=1/4.