Probability
posted by Anonymous .
A pair of dice is rolled, one black and one white. Find the probability of each of the following events.
1. The total is between 3 and 7.
My answer: 1/3
2. The total is 13.
My answer: 0
3. The numbers are 2 and 5.
?????????
4. The black die has 2 and the white die has 5.
??????
5. The black die has 2 or the white die has 5.
??????

#1: I get 20/36 = 5/9
B:1 & W:2,3,4,5,6
B:2 & W:1,2,3,4,5
B:3 & W:1,2,3,4
B:4 & W:1,2,3
B:5 & W:1,2
B:6 & W:1
#2 ok
#3: 2/36 = 1/18
B:2 & W:5
B:5 & W:2
#4: 1/6 * 1/6 = 1/36
#5: 1/6 + 1/6 = 1/3
You can list all 12 events if you want