Silly that he messes up the first example, but I've wanted something like this third solution when sorting by rating on Amazon -- when a product has only a couple of positive reviews, it's almost the same as being unreviewed. (On the other hand, just a couple of negative reviews can often be quite helpful, since they can list concrete problems making the product bad -- a positive review has the much harder case to make of "there will be nothing bad about this product".)