A minimum age is the youngest the object can possibly be.
A maximum age is the oldest the object can possibly be. But they obviously have to have been made first, so 1920 is the maximum age of the burial.
But there are some questions that come to mind: Calculus students typically meet this problem somewhere in the second semester.
If the decay constant is very small, even tiny amounts of contamination by other radioactive materials can be very significant.Rubidium-strontium dating is more robust, and uranium-lead dating can survive fairly significant metamorphism without resetting.If a system gains or loses isotopes in a predictable way, it may be possible to estimate the loss and correct the age.Sedimentary rocks are generally hard to date because common cements like silica don't have datable radioisotopes, and minerals like glauconite that are common in sedimentary rocks are very prone to resetting.If only there were long-lived isotopes of silicon, calcium, and magnesium!
In calculus terms, we write: d N(t)/dt = -K * N(t) or d N(t)/N(t) = -K dt The minus sign means that each decay decreases the total number of atoms.