Auto-translated
Freebies, S&P 500! Portugal will pass (85%), Ukraine (75%), Russia (100%), and France (95%).
If we believe this data, then 0.85 x 0.75 x 1.00 x 0.95 = 0.605625, rounding up to 60%.
Oelm has a 40% chance, which means that by betting 500, Oelm will win 750.
In my opinion, the probability of victories (especially Russia) is overestimated.
I think Portugal has an 80% chance (0.8); Ukraine 0.6; Russia 0.7; France 0.8.
The probability of four events is 0.2688.
It turns out that Cobra has approximately 3 times less chance of winning, according to my data. Therefore, in order for Oelm to get 500, he needs to bet 1500.