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You and your friend are rolling number cubes. Each cube has 6 sides with the numbers 1 to 6. If a sum of 7 is rolled, your friend gets a point. However, you get a point if either one of the sums listed below is rolled. Which pair of numbers would make the game fair?

2 and 12
2 and 5
12 and 8

2 Answers

3 votes

Answer:

2 and 5

Explanation:

Let's list all the possible combinations of numbers that would result in you winning:

1 + 6 = 7

2 + 5 = 7

3 + 4 = 7

4 + 3 = 7

5 + 2 = 7

6 + 1 = 7

There are six combinations that would result in you winning. To make the game fair, the probability of each outcome should be equal.

Since each cube has 6 sides with numbers 1 to 6, the total number of possible outcomes is 6 * 6 = 36.

The probability of your friend winning (rolling a sum of 7) is 6/36, which simplifies to 1/6.

To make the game fair, you should also win with a probability of 1/6. Since there are six combinations that result in you winning, each combination should have a probability of 1/6.

However, we can see that the combinations (1, 6) and (6, 1) are essentially the same, as they result in the same sum. Similarly, (2, 5) and (5, 2), as well as (3, 4) and (4, 3), are equivalent pairs.

Considering this, we can choose one representative pair from each set of equivalent pairs. Let's choose (1, 6), (2, 5), and (3, 4) as the representative pairs.

Therefore, the pair of numbers that would make the game fair is (1, 6), (2, 5), and (3, 4).

User Nikel Weis
by
7.9k points
3 votes
Sum ---- Combinations
2 --------- 1
3 --------- 2
4 --------- 3
5 --------- 4
6 --------- 5
7 --------- 6
8 --------- 5
9 --------- 4
10 ------- 3
11 ------- 2
12 ------- 1

7 has 6 combinations.
Now,
2 and 12 ---- 1+1 = 2
2 and 5 ------1+4 = 5
12 and 8 ---- 1+5 = 6

12 and 8 would, therefore, make the game fair.
User Jermy
by
6.8k points