Instead of finding the probability of this event directly, we will find the probability of the non-occurrence of this event and subtract it from 1 to get the required probability.
Combination whose sum of 12 is (6,6)
Combinations whose sum of 11 is (5,6), (6,5).
Therefore, there are totally 3 occurrences out of 36 occurrences that satisfy the given condition.
Probability whose sum of two numbers is greater than or equal to 11:
Hence probability whose sum of two numbers is lesser than 11: