The rubber ball used in ancient ball games weighed between 3 to 15 kilos.

Evidence

The rubber ball was heavy – it could weigh anywhere from 3 or 4 kilos (8 lbs) to almost 15 kilos (30 lbs) — Neil MacGregor, A History of the World in 100 Objects, 615

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 615