Is there a significance of polygraph scors like say +9 +10 +11 and so forth? What is the highest and lowest score that you can attain and pass?
While there are different scoring methods, typically a score of +3 or higher is considered passing, a score of -3 or lower is considered failing, and scores between these two values are deemed inconclusive.
Polygraph charts are scored by comparing reactions to relevant questions with reactions to so-called "control" or comparison questions. For more on polygraph procedure, see chapter 3 of The Lie Behind the Lie Detector:
https://antipolygraph.org/lie-behind-the-lie-detector.pdf
In response to polygraph scores, I submit the following image of a tube tester. ;)
(http://www.radiomuseum.org/images/radio/triplett_electrical/3413_a_tube_tester_541947.jpg)