Stacy rolled a cube numbered 1 through 6 two times. what is the probability that the sum of the rolls was 7?

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7 can be obtained by the following two throws:

1,6
6,1
2,5
5,2
3,4
4,3

6/36 = ?

To find the probability of rolling a sum of 7, we need to determine the total number of possible outcomes when rolling the two dice and the number of outcomes that result in a sum of 7.

Let's start by listing all the possible outcomes for rolling two dice. We can use a grid to illustrate this:

| 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 |
2 | 3 | 4 | 5 | 6 | 7 | 8 |
3 | 4 | 5 | 6 | 7 | 8 | 9 |
4 | 5 | 6 | 7 | 8 | 9 |10 |
5 | 6 | 7 | 8 | 9 |10 |11 |
6 | 7 | 8 | 9 |10 |11 |12 |

In this grid, each number represents the sum of the values obtained on the two dice. For example, when rolling a 1 and a 1, the sum is 2.

Now, let's count how many outcomes result in a sum of 7. We can see that there are six possible outcomes: (1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1).

Therefore, the probability of rolling a sum of 7 is 6 out of the total number of possible outcomes, which is 36 (6 numbers on a die multiplied by 6 numbers on a die).

So, the probability is 6/36, which simplifies to 1/6, or approximately 0.1667.