Aristocrat publishes none of these. The 87.97% is the machine's own statement, reproduced in a published Federal Court judgment. The 85%, 87.5% and roughly-90% figures come from the Australian Institute of Family Studies and Liquor & Gaming NSW.
Dolphin Treasure is rated low by slotjava and onlinepokies4u, low to medium by betsquare, and undisclosed by chipy — while pokiespros manages to describe it as high volatility in one place and low in another on the same page.
House edge, in dollarsWhat "house edge" means once it is in dollars
The Australian Institute of Family Studies puts the general position bluntly: the price of an EGM game is 1 minus its return, so an 85% machine charges 15% of everything wagered, and “the 'house edge' for Australian EGMs is as high as 15%”.