Hello there

You can calculate your composite score for DU JAT but it's quite tough to predict the ranks .As ranks depends upon a lot of other factors like number of students attended ,maximum marks ,minimum marks ,year ,and other scenarios .So you can just calculate the composite score .Take 65 percentage of your jat score and 35% of your board percentile ,and then add them .This is your composite score .

However you not need to calculate the rank as well as du will mention your rank when the results will be out .