Each of the two PI assessment tests is scored differently.
For the cognitive assessment, scores range from 100 to 450, with 250 representing the average across all test-takers. The 250 score corresponds to a raw score of about 20 out of 50 questions answered correctly, so if you pass that, you'll be above average. That doesn't mean you pass, however. Every company sets its own passing threshold for each job.
The behavioral assessment doesn't really have a traditional scoring system with "good" and "bad" results. Your personality profile is either a good fit or not for the role, but no profile is inherently negative. You'll want a result that reflects the values your employer cares about, but you also want to be honest. Don't get stuck in a job that doesn't fit you, drives and values.