How is XP gain calculated?

Question

Hello.

How is your gained exp calculated?

I have found that I can not make the math add up when I try to arrive at the same number as I actually recieve.

Background:
I made a solo hunt in mother of scarabs lair on 225% and with exp preys 10/10 (40%) on ancient scarabs and bone beasts.
https://imgur.com/a/wX2f9Ns

In this picture you can see the mobs I killed, note however that I killed 2 ancient scarabs 1 bonebeast and 1 necromancer on 150%
https://imgur.com/a/QaHheaV

When I calculate the exp gained on 100% for all except the mobs killed on 150% I get gained exp = 313,7k;
which on on 225% = 705,825
+ mobs killed on 150% = 3,9k
+ prey exp = 120,608k
----------------------------
Total = 830,3k

So we are missing around 55k exp which is equivalent of 6,6% of the total exp I calculated (quite a big error).

If we would calculate all mobs as killed on 225% we would get:
Mobs = 711,675k
Preys = 121,416k
----------------------------
Total = 833,091

Which is still 52k exp shy of what it should be.

Comments

I did not do the math myself, nontheless, I'm confident the totals are correct.
My thoughts on why the presented math may be wrong are:

225% is for 30 minutes only. (Unless boosted with TC)
    Meaning, if on the first 30 minutes you killed only 1 AC, the math would already be wrong.
The presented preys have different minutes remaining, meaning one has been activated before/after the other, perhaps on the running time the mobs you killed are different than the 'after hunt' math.
There are other things to point out but those two are, most likely, the reason the presented math is incorrect.

Answer 1

Answering your question the exp Gain is calculated just on values of amount of exp of the monsters plus the % on the stamina and or bost/prey. There is no more mistery than that.

Also there is a passive on low levels for that