What is the probability that getting a total of the numbers on the dice is 6 ?

For the next two (02) items that follow : Four dice are rolled.

  1. A. \frac{1}{216}
  2. B. \frac{1}{324}
  3. C. \frac{5}{648}
  4. D. \frac{7}{648}

Correct Answer: C. \frac{5}{648}

Explanation

We need the number of solutions to x1+x2+x3+x4=6 with xi >= 1. Let yi = xi-1. We want y1+y2+y3+y4=2 with yi >= 0. Combinations = (2+4-1)C(4-1) = 5C3 = 10. Total outcomes = 6^4 = 1296. Probability = 10/1296 = 5/648.

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