The exponential function for the amount of plutonium-244 remaining as a function of time is given by:
[tex]A(t) = A(0)e^{-0.00000000866t}[/tex]
A decaying exponential function for the amount of a substance is modeled by:
[tex]A(t) = A(0)e^{-kt}[/tex]
In which:
The half-life of plutonium-244 is 80,000,000 years, hence [tex]A(80000000) = 0.5A(0)[/tex], which is used to find k.
[tex]A(t) = A(0)e^{-kt}[/tex]
[tex]0.5A(0) = A(0)e^{-80000000k}[/tex]
[tex]e^{-80000000k} = 0.5[/tex]
[tex]\ln{e^{-80000000k}} = \ln{0.5}[/tex]
[tex]-80000000k = \ln{0.5}[/tex]
[tex]k = -\frac{\ln{0.5}}{80000000}[/tex]
[tex]k = 0.00000000866[/tex]
Hence, the function is:
[tex]A(t) = A(0)e^{-0.00000000866t}[/tex]
You can learn more about exponential functions at https://brainly.com/question/25958656