Percentage: marks obtained over total marks
68 marks out of 100 gives 68 ÷ 100 × 100 = 68%. This is the same simple percentage calculation regardless of what total marks the exam was scored out of.
Letter grade uses a fixed scale
On the common absolute scale used here (A at 90%+, B at 80%+, C at 70%+, D at 60%+, F below that), 68% falls in the D range. A much higher score, 92%, would land in the A range instead.
Pass/fail is a separate, independent check
Passing isn't about the letter grade at all — it only compares the percentage against the exam's own pass mark. At a 35% pass requirement, 68% clears it comfortably and passes, despite landing in the "D" letter-grade range. A 30% score, though, falls below that same 35% pass mark and fails outright — regardless of what letter grade a 30% might otherwise suggest.
Why grade and pass status can tell different stories
A D grade sounds unimpressive on an absolute A-F scale, but it can still be a comfortable pass if the actual pass requirement is much lower than the D cutoff — which is exactly the case for many Indian exam boards, where pass marks commonly sit around 33-40% while the letter-grade scale used for reporting starts much higher.