Its confusing isn't it. The maximum possible score in each paper is 140 but a child does not have to get every question right to get this mark. Depending on age a child would need to get around 75% of the questions right. I don't know why they have this 140/75% cut off. Does anybody else know the logic underlying this methodology?
The scores are standardised so I think 100 is the 'average' score 120 is the minimum score for GS and 140 is the maximum score.
Judd state on their website that a raw score (this is the score before it is standardised) of 75% normally equates to 140.
So if a test has 50 questions on it and the child manages to get 25 correct so 50%, going by the figures on the Judd website, the child will have a standardised score of about 120. If say the child got 40 questions correct so 80% this would normally give a standardised score of 140.
There are other threads on this forum about standardised scores but I don't know how to link them.
If you look further down the Kent forum, probably on pages 2 or 3 you will find one from just last week.
But basically the idea of standardisation is to find the top percentage of pupils, so the raw score will vary depending if the paper is easy or not.