Single correct option
Two fair dice are thrown together. What is the probability that the sum of the numbers shown is a prime number?
- A. 5/12
- B. 1/3
- C. 7/18
- D. 1/2
Show answer and solution
Answer: (A) 5/12
Possible prime sums: 2, 3, 5, 7, 11.
Number of outcomes: sum 2 → 1, sum 3 → 2, sum 5 → 4, sum 7 → 6, sum 11 → 2. Total = 15.
Probability = 15/36 = 5/12.
Tip: The number of ways to get sum s with two dice is 6 − |s − 7|.
Number of outcomes: sum 2 → 1, sum 3 → 2, sum 5 → 4, sum 7 → 6, sum 11 → 2. Total = 15.
Probability = 15/36 = 5/12.
Tip: The number of ways to get sum s with two dice is 6 − |s − 7|.
Saved on this device. Sign in or create a free account to keep it on every device.