Originally Posted by

**noplacebos** So, I know that there are some teflon balls (not drawable) in my 2 urns. **I am suspecting that the remaining sets of steel balls are disjoint** between the 2 urns.

A working example:

Urn A, 20 draws with replacement, [1,2,3,4,5,6,7,8,9,10] the outcomes.

Urn B, 20 draws with replacement, [13,14,15,16,17,18,19,20] the outcomes.

Can I calculate the probability, no matter how small or big,

that in urn A, balls [13-20] are in teflon, given that they were not drawn in the first 20 trials,

**AND**

that in urn B, balls [1-10] are in teflon, given that they were not drawn in the first 20 trials.