What is the percentile system in the DU JAT 2019 result What does it mean

The percentile released by NTA and not DU. So nothing is official right now.

Your percentile score will tell you how less your marks are in comparison of the highest score scored by a candidate. For example 100 percentile does not mean they have scored full marks. Its means that their score is the highest out of all the candidates and their rank in No. 1. Similar candidates with 99.99 percentile will have rank 2.

But here are you may see there are many students with similar percentiles. But that will not matter because their Best of Fours maybe different. And even of that is same then whoever was born first will be given the higher rank. All these conditions were specified by DU itself in their Bulletin.

So now wait for the official DU rankings

All the Best

Hello Dear aspirant,
Hope you are doing well!!
A percentile is a unit used to measure the percentage of students below or above you in the merit list. For instance, if you have got 80 percentile in your CAT exam that means 80% of students who appeared in the exam scored less than you.
Percentile system is basically the minimum qualifying percentage that is required to qualify the exam. Like -
Applicants must obtain a minimum of 60 per cent in the qualification examination.

Candidates belonging to SC/ST/CW/PwD category requires minimum 55 per cent, while OBC (Non-creamy) category candidates require 54 per cent, at the senior secondary level.
So, I I hope I have cleared your query.
Best of luck!!