Question

A group of friends try out a new game that uses a pair of ordinary, fair dice. Points are given to players based on the sum of the two numbers from the rolled pair of dice. If the sum is between 2 and 5, inclusive, the amount of points awarded is the sum minus 1. If the sum is between 6 and 9, inclusive, the amount of points awarded is the sum minus 3. If the sum is between 10 and 12, inclusive, the amount of points awarded is the sum minus 5. Calculate the probability of earning exactly 5 points.

Answer 1

0.2222 = 22.22% probability of earning exactly 5 points.

Explanation:

A probability is the number of desired outcomes divided by the number of total outcomes.

Possible outcomes:

For the pair of dice:

(1,1), (1,2), (1,3), (1,4), (1,5), (1,6)

(2,1), (2,2), (2,3), (2,4), (2,5), (2,6)

(3,1), (3,2), (3,3), (3,4), (3,5), (3,6)

(4,1), (4,2), (4,3), (4,4), (4,5), (4,6)

(5,1), (5,2), (5,3), (5,4), (5,5), (5,6)

(6,1), (6,2), (6,3), (6,4), (6,5), (6,6)

So 36 total outcomes.

If the sum is between 6 and 9, inclusive, the amount of points awarded is the sum minus 3.

Sum of 8 -> 5 points awarded. So

(2,6), (3,5), (4,4), (5,3), (6,2): 5 outcomes.

If the sum is between 10 and 12, inclusive, the amount of points awarded is the sum minus 5.

Sum of 10 -> 5 points awarded. So

(4,6), (5,5), (6,4): 3 outcomes.

Desired outcomes:

5 + 3 = 8

Calculate the probability of earning exactly 5 points.

`p = (D)/(T) = (8)/(36) = 0.2222`

0.2222 = 22.22% probability of earning exactly 5 points.