The mass of a radioactive substance remaining after days is modelled by grams

MATHEMATICS · Single correct · AP · AP Precalculus · Exponential and Logarithmic Functions · Exponential and Logarithmic Functions

Problem

The mass of a radioactive substance remaining after

t

days is modelled by

M(t)=120 e^{-0.08 t}

grams. If the counting starts at the instant the measurement begins, which of the following is the most reasonable domain for the function

M

? (a)

\{t\in\mathbb{R}\mid t\le 0\}

(b)

\{t\in\mathbb{R}\mid t\ge 0\}

(c)

\{t\in\mathbb{R}\mid 0\le t\le 120\}

(d)

\mathbb{R}