Can someone please clarify the apparent lack of uniformity of the Experience Points?

Question

The Experience Points (XP) in Microsoft Learn (course: PL-300) cause a lot of questions. Here they come:

[EDITED!] I did wonder how I could have 14,250/16,199 and at the same time 46,550/48,499 XP. Because different pages show different totals, it became confusing. After reaching level 8, it became clear that the 1st set of points refer only to the progress of reaching the next level, while the 2nd set is cumulative.
As higher levels are reached, each level requires more XP to reach than the ones before, I noticed.

Two questions remain:
1.) Sometimes a knowledge check grants 200 XP, and sometimes 400 XP is granted. Why so?
2.) And how can the total XP end on 250 points, while all the scores per unit have a double zero as last 2 digits? Or which part of PL-300 has a score that doesn't end on double zero?

Anyone who can clarify some of these things? I get a somewhat arbitrary feeling from this system.

PS- The tag I used is off. I searched for any relevant word, but couldn't find a match. I will apply suggestions.