When two dice are thrown simultaneously what is the probability that the sum of two numbers that turn up is less than 11?

In the experiment of throwing two fair dice the probability of having 11 or 12 as the

sum of the two numbers that turn up is:

P(x=12) = 1/36, and P(x=11) = 2/36

So, P(x<11) = 1 - [P(x=12) + P(x=11)] = 1 - 3/36 = 33/36 = 0.91666...

≈ 91.7%