Using an exponential function, it is found that 4 mg of the substance would still be left after 32 days.
<h3>What is an exponential function?</h3>A decaying exponential function is modeled by:
In which:
- A(0) is the initial value.
- r is the decay rate, as a decimal.
In this problem, considering that the initial amount if of 64 mg, and we are working with half-lifes, the equation is given by:
32 days is 32/8 = 4 half-lifes, hence the amount remaining in mg is given by:
More can be learned about exponential functions at brainly.com/question/25537936