Dear Harsh, to be eligible for IBSAT, you should have secured a minimum aggregate of 50% in your Graduation. This aggregate is calculated for all the 3 years and not for a single year. Please visit our page for more information: https://bschool.careers360.com/articles/ibsat-eligibility-criteria

Going by this, if you have aggregate less than 50%, you cannot appear for IBSAT though your final year aggregate is more than 50%.