To find the probability of rolling a sum less than 11 with a pair of standard six-sided dice, we can enumerate all possible outcomes and count the favorable outcomes.
The possible outcomes when rolling two six-sided dice are combinations of numbers from 1 to 6 on each die. There are \(6 \times 6 = 36\) total outcomes.
Now, let's consider the favorable outcomes where the sum is less than 11:
- If the sum is 2, there is only one combination: (1, 1).
- If the sum is 3, there are two combinations: (1, 2) and (2, 1).
- If the sum is 4, there are three combinations: (1, 3), (2, 2), and (3, 1).
- If the sum is 5, there are four combinations: (1, 4), (2, 3), (3, 2), and (4, 1).
- If the sum is 6, there are five combinations: (1, 5), (2, 4), (3, 3), (4, 2), and (5, 1).
- If the sum is 7, there are six combinations: (1, 6), (2, 5), (3, 4), (4, 3), (5, 2), and (6, 1).
- If the sum is 8, there are five combinations: (2, 6), (3, 5), (4, 4), (5, 3), and (6, 2).
- If the sum is 9, there are four combinations: (3, 6), (4, 5), (5, 4), and (6, 3).
- If the sum is 10, there are three combinations: (4, 6), (5, 5), and (6, 4).
Adding up the favorable outcomes, we get \(1 + 2 + 3 + 4 + 5 + 6 + 5 + 4 + 3 = 33\).
Therefore, the probability of rolling a sum less than 11 is the ratio of favorable outcomes to total outcomes:
\[ P(\text{sum less than 11}) = \frac{\text{Favorable outcomes}}{\text{Total outcomes}} = \frac{33}{36} \]
Simplifying the fraction, we get:
\[ P(\text{sum less than 11}) = \frac{11}{12} \]
So, the probability of rolling a sum less than 11 is \( \frac{11}{12} \).