Multiple choice

Two dice are rolled. What is the probability that the total score is not a prime number?

  1. 5/12

  2. 7/12

  3. 11/18

  4. 1/2

  5. 7/13
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total outcomes = 36. Prime sums are 2, 3, 5, 7, 11. Counts: 2(1), 3(2), 5(4), 7(6), 11(2) = 15 outcomes. Non-prime sums = 36 - 15 = 21. Probability = 21/36 = 7/12.

AI explanation

Use the classical definition of probability to find the chance of rolling a non-prime sum. The sample space of rolling two dice has 36 outcomes, and the possible sums are 2 through 12. The prime sums are 2, 3, 5, 7, and 11, which account for 15 total combinations, leaving 21 combinations for the non-prime sums of 4, 6, 8, 9, 10, and 12. Therefore, the probability is 21 divided by 36, which simplifies to 7/12. The answer is 7/12.

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