we computed the probability of getting X>= 10 from two options. A: X=sum of 3 d10, B: X= max of 2 d20. The result was: P(X>=10 | A) = 0.916, and P(X>=10 | B) =0.7975

Now let's add another layer: I choose either option A (20% of the time), or option B (80% of the time). You don't know which option I chose this time, but you know I ended up with X>=10.

Given the above outcome, what is the probability that I chose option A?