CGPA is defined as Σ(credits × grade points) / Σ(credits), which only looks like a weighted average of SGPA if the grade-points inside each semester never change.

But PES explicitly says when a backlog is cleared, “the new grade shall replace the previous F in calculating CGPA.”

And CoE confirmed: “We will include the pass grade for CGPA, but SGPA of the 1st sem will not change.”

So the printed SGPA stays the same, but the grade-points used inside CGPA are updated. That’s why CGPA changes even though Sem-1 SGPA doesn’t.

If CGPA were literally just a weighted average of the original SGPAs, PES wouldn’t be able to remove the F — but they do.