Answer:
Step-by-step explanation:
If I'm understanding this correctly, the rate of decay function is
[tex]f(x)=1000(.5)^{\frac{x}{30}}[/tex]
and we want to solve for the amount of element left after x = 40 years. That would make our equation
[tex]f(40)=1000(.5)^{1.33333333333}[/tex]
Multiply the repeating decimal by .5 to get
f(40) = 1000(.3968502631)
and f(40) = 396.85
So no, it's not safe for human habitation.