Pet exp penalty question

[krforrester]

If the mob has 1200 hp's and the pet's DS does 150 damage, does that mean I have to do more than 525 damage to get full exp? 1200 - 150 = 1050 x 50% = 525.

Or, given the same pet DS, do I have to do more than 600 damage? 1200 x 50% = 600.