Two fair dice are rolled. What is the probability that the sum is 7?

Two fair dice are rolled. What is the probability that the sum is 7?

Approach: Count favorable outcomes and divide by total outcomes.

6 favorable outcomes: (1,6), (2,5), (3,4), (4,3), (5,2), (6,1). Total outcomes: 36. Probability = 6/36 = 1/6.

Follow-up: What is the probability that the sum is prime?

Key concepts: sample space, counting, uniform distribution.