99% is NOT AIR 5
Sorry to break the bubble for a lot of people here but it is basically pointless to bother about All India Rank in an exam that is NEITHER a competitive exam NOR an exam where fairness of marks is guaranteed for all (different teachers check your copies and few of my friends got 100 despite making blunders in the paper.)
I personally got 99.5 and my school is publicizing me as AIR 3 which is honestly so embarrassing as a jee aspirant. They are trying to borrow the aura of AIR that comes from JEE or NEET.
Know that only about 1.5 L appear for ISC which is actually a pretty small number relative to CBSE or JEE/NEET.
Most brilliant students (atleast in Science) don't even bother about Boards so they give little fight here.
And there are hundreds of people above this supposed AIR 3. So you mean 90% --> AIR 41 and 0% --> AIR 401? That is not how AIRs work.
If you are in Science Stream and wish to go into engineering or medicine (like majority) 99.5% is no better than someone who got 90%.
Atp I'm just ranting coz I needed to get this across. Point is, don't bother about AIR in boards there is no such thing.