What’s the probability of rolling two numbers whose sum is 7 when you roll two dice? The table below shows the outcome of ten trials in which two dice were rolled.

a. List the trials that had a sum of 7.

b. Based on these data, what’s the empirical probability of rolling two numbers whose sum is 7?
Trial         Outcome
1   . . . . . . . . . . . 3, 1
2   . . . . . . . . . . . 1, 2
3   . . . . . . . . . . . 6, 5
4   . . . . . . . . . . . 6, 4
5   . . . . . . . . . . . 5, 2
6   . . . . . . . . . . . 6, 6
7   . . . . . . . . . . . 3, 2
8   . . . . . . . . . . . 2, 1
9   . . . . . . . . . . . 4, 6
10 . . . . . . . . . . . 1, 6