Quote:
x + (x/2) = Highest level you can group with and get exp. This is the formula you can use to see if you will get exp with someone or not.
This applies only to regular experience after the TSS patch. AA experience is based off the /con of the mob from the highest level person in the group.
So, the level 50 and 70 are grouped together, and they are fighting mobs that are grey to the level 70. When the mob dies, the experience is still divided based on level. Since the mob is grey to the level 70, they do no get their share of the exp. It poofs. The level 50 will then get their shared of the exp.
This is still nice exp for the level 50 since you should be clearing mobs at a much faster pace with the level 70 doing a bulk of the killing.
I don't know if they changed the rules regarding pets, but it used to be that if the pet did 100% of the damage that 50% of the exp poofed due to the pet.