The program
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Expected output
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Aarav -> 92% Grade: A+Isha -> 72% Grade: BKabir -> 31% Grade: Fail
How it works
Each student is an object with a naam and a list of marks, and all students sit in one list. The outer loop visits each student; the inner loop adds up that student's marks.
The percentage is the average rounded with ganit.round (each subject is out of 100). grade_batao checks the bands from highest to lowest and returns the first match, so 92 becomes A+ without also matching the lower bands.
pct + "%" joins the number and the percent sign into one piece of text.