Maybe you're aware of how Rotten Tomatoes scores work, but in case someone reading this isn't: the score is not some average of individual scores like IMDb uses (I think), but just the _proportion of critic scores that are positive_.

So, if a film has 100x 2.5/4 star ratings from critics and 50 1.5/4 star ratings, it would have a Tomatometer score of 67% (100 positive of 150 ratings).