Machshirin 2:9

If someone found meat, we proceed according to the majority of butchers. If the meat was cooked, we proceed according to the majority of people who eat cooked meat.

Machshirin 2:10

Let’s say that someone found produce on the road. If most landowners bring their produce into the house, he need not tithe the produce; if they take it to market, he must tithe it. If they’re 50/50, it’s of doubtful status. Let’s say that there’s a storehouse where both Jews and non-Jews put grain. If most are non-Jews, it’s certainly untithed; if most are Jews, it’s of doubtful status. If they’re 50/50, it’s certainly untithed; this is the opinion of Rabbi Meir. The Sages say that even if all of them are non-Jewish, if even one Jew adds his grain, it’s of doubtful status.