First, do remember that we do look at three different areas when shortlisting students (https://riadmissions.freshdesk.com/support/solutions/articles/51000176228-how-will-you-shortlist-students-academic-domains-).
As to whether we can share the minimum percentage / marks a student should attain (in the subject / overall), the simple answer is we are not able to do that because this is dependent on (1) on the cohort of students applying to us in that particular year and (2) the student's performance in the other 2 areas (if any).
If parents really need a rough guide, then they can consider the child's academic performance with reference to other students in their school. But do remember that just because he is performing very well or not as well, it doesn't mean he will / will not get shortlisted as this is only one out of three areas we look at.