Wu rolls two fair, six-sided dice. You are not told what the rolls were, but you are told that the sum of the two rolls is a prime. What is the probability that the sum of the two rolls is $2$?
The possible outcomes are 2,3,5,7,&11
There is only 1 way to get a 2, since 1 and 1 is the same as 1 and 1
So the probability is 1/5
Gave my best shot, hope it helped!
The sample space for 2 dice is as follows:
(2, 3, 3, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 11, 11, 12)>>Total = 36
There are 15 ways of making up a prime number on a roll of 2 dice, but only one way of making up a 2, and that is: 1 +1 ==2,
Therefore the probabikity is: 1 / 15 ==6.67%
