A 12-sided die is rolled. The set of equally likely outcomes is $\{1,2,3,4,5,6,7,8,9,10,11,12\}$. Find the probability of rolling a number less than 9 . The probability of rolling a number less than 9 is (Type an integer or a simplified fraction.)

Step 1 ：A 12-sided die is rolled. The set of equally likely outcomes is \{1,2,3,4,5,6,7,8,9,10,11,12\}. We are asked to find the probability of rolling a number less than 9.

Step 2 ：The total number of outcomes when rolling a 12-sided die is 12. The outcomes that are less than 9 are \{1,2,3,4,5,6,7,8\}, which is 8 outcomes.

Step 3 ：The probability of an event is calculated by dividing the number of favorable outcomes by the total number of outcomes. In this case, the probability of rolling a number less than 9 is \(\frac{8}{12}\).

Step 4 ：This fraction can be simplified to \(\frac{2}{3}\).

Step 5 ：Final Answer: The probability of rolling a number less than 9 is \(\boxed{\frac{2}{3}}\).