@Wisdom_HQ Fill 13
Empty into 5 (8 left) and dump 5
Empty 8 into 5 (3 left) and dump 5
Empty 3 into 5
Fill 13
Empty the space for 2 from 13 into the 3 in 5
11
@MercuriusFilius Assuming the person picking is blindfolded, the bucket size is negligent, and you can't remove all the white balls....
1 black ball in 2 buckets, and 48 black balls in the bucket with the 50 white balls. Guarantee black in 2 buckets and slightly less than 50/50 in the third