Hi oop,
I'm not sure what you are asking, but I will talk about the difference between percentile and percentage. Maybe others who read this will be able offer a better answer, more tailored to your question.
The percentile is a rating/ranking among others who took the test and therefore depends upon how many correct answers were given in comparison with how well others scored... not how many answers were correct as a percentage of the total number of questions asked.
If your child gave more correct answers on the current test (higher percentage) than on a prior test, and yet their score was shown as a lower percentile, this would indicate that the group or cohort of children being compared scored somewhat higher than your child.
To recap...
Percentage:
Your child's score as compared with the number of questions asked.
For example: 99 out of 100 = 99%
Percentile:
Your child scored better than what proportion of students in the comparison group or cohort.
For example: Your child scored better than 97% of students in the comparison group or cohort.
