Mathilde made in total 13 rolls (that we saw) across the examination turn proper. The average result was 62.75, (off a total of 817)- which maybe seems good-but-not-exceptional, until you realise that according to Anydice, there was only a 6.26% chance of rolling that high or better.
Given Ranald could (edit- and did!) stop weighting the odds at the point we won the first duel (in two seconds), we could also consider that we averaged (557/8) ~69 across the 8d100 until graduation was in the bag. Anydice giving us a 3.05% chance of rolling at least that high... I think it's fair to say we performed pretty exceptionally... luckily.
(In other words, if the graduation exam was a single roll, we rolled a 95, or a 98.)