Answer
a. $100$ percent.
b. $68.5$ percent.
c. $30.8$ percent.
d. $20$ percent.
Work Step by Step
a. Given the function $f(x)=80e^{-0.5x}+20$, with $x=0$, we have $f(0)=80e^{0}+20=80+20=100$ percent.
b. Let $x=1$; we have $f(1)=80e^{-0.5}+20\approx68.5$ percent.
c. Let $x=4$; we have $f(4)=80e^{-0.5(4)}+20\approx30.8$ percent.
d. Let $x=52$; we have $f(52)=80e^{-0.5(52)}+20\approx20$ percent.
