LOL. Are you really relying on the numbers on IMDB? The numbers of the separate episodes of Pearson are: 7.7, 8.4 and 9.1. In terms of numbers, you have to take that site with a sprinkler :)
How do you explain the big difference in numbers? This is not only the case with Pearson, there are different series where the figures differ enormously. I have also come across series that had yet to start and already had a grade.