A 25 mg sample of wood produced 3072 β− particles from carbo…

A 25 mg sample of wood produced 3072 β− particles from carbon-14 in 3 hours, while a 25 mg sample of fresh wood produced 9216 β− particles in the same period of time. The half-life of carbon-14 is 5730 years. How old is the wood from the archaeological site?