I consulted standard reference sources on the death camps, Belzec, Sobibor, Treblinka: The Operation Reinhard Death Camps, for the dimensions of the mass graves..........When Arad says that Treblinka had five mass graves that were 50 meters by 25 meters by 10 meters, I believe him........I will now do the math. Seven hundred thousand people buried in five mass graves. Each mass grave is 50 meters by 25 meters by 10 meters. 5 X 50 X 25 X 10=62,500 cubic meters. 700,000/62,500=11.2 bodies per cubic meter.