Answer:
29 years
Step-by-step explanation:
- Given the function [tex]f(x)= 200(0.5)^{\frac{x}{50} }[/tex], where x stands for the number of years since the material was put into the vault, we can plug 140 into x to find the amount leftover.
- Another way of doing this is to change the function to [tex]f(x)=200(0.5^{\frac{1}{50} })^{x}[/tex] which are equivalent functions, and then plug 140 into x. This function is helpful if you also needed to find the rate.
- I'll use the 1st function because the question doesn't ask for the rate
[tex]f(x)= 200(0.5)^\frac{140}{50}}[/tex]
From here I'll just use a calculator & get 28.7, or 29 years.
