The exponential function that gives the sample mass in grams is:
[tex]s(t) = 450\left(\frac{1}{3}\right)^t[/tex]
A decaying exponential function is modeled by:
[tex]A(t) = A(0)(1 - r)^t[/tex]
In which:
In this problem:
Then, the mass is given by:
[tex]s(t) = A(0)(1 - r)^t[/tex]
[tex]s(t) = 450\left(1 - \frac{2}{3}\right)^t[/tex]
[tex]s(t) = 450\left(\frac{1}{3}\right)^t[/tex]
More can be learned about exponential functions at https://brainly.com/question/25537936