I am interested to know, according to written law, if there is something like a ratio or relativization to consider between people of the tribe and gentiles that a Jew is bound to. Is there's such a thing, generally, as a rule in Judaism along the lines of "One Jew is worth N gentiles"?
Some examples of dilemmas in which such a rule might apply:
For a group-project in university i have been asked by 3 gentiles to join there group. After this i was asked by 2 Jewish persons (secular like me) to join their group. I am quite good in the subject and i know my participation would be helpful for each group.
Considering that there doesn't exist any strong relationship with any of the persons involved, is there an obligation for me to prefer the people with the same culture (religion)?
Imagine I can save a gentile by risking my life with a chance of dying at 51%. Shall i, according to written law, do it? your answer can consider a floating variable other than 51. (Let's assume that I don't know anything about the righteousness of the gentile.)
Imagine 2 boats, 1 with 10 people of the tribe and 1 with 20 gentiles. My ship has 20 places to rescue people but because of fuel, I can only make it to save one boat. Which shall happen according to law? (Again, assume that I don't know anything about the qualities of any of the people involved other than their religious affiliation.)
Please consider that this are hypothetical cases. In such situations our heart will tell us without a doubt what to do, but for the purpose of this exercise only reason and law can be considered.