The number is not unreasonable given all the potential variables.
Go to the wensite i listed below. the PDF file contains information on average expected yiedl given the size and age of the animal. They have several more pubs of interest related to big game as well. A decent bull or big cow can produce around 200lbs of boneless and it goes down from there
www.wyomingextension.org/agpubs/pubs/B594R.pdf