Question

If there are two red and blue dice. Find the probability when the sum of the dice is a prime number, where the number on red is more than blue.

• A. 1/12
• B. 5/36
• C. 7/36
• D. 1/9

Hint:

For probability questions with dice, focus on the favorable outcomes and divide by the total possible outcomes (36).

Answer 1

The Correct Option is B

The possible prime numbers that can be the sum of two dice are 3, 5, 7, and 11.
For each of these sums:
- 3: (1,2)
- 5: (1,4), (2,3)
- 7: (1,6), (2,5), (3,4)
- 11: (5,6)
Out of these, only the pairs where the number on the red die is greater than the blue die are considered. The favorable pairs are:
- (2,1), (3,2), (6,1), (5,2), (6,5)
Thus, the probability is: \[ P = \frac{5}{36} \]