#### Answer

a) 100%
b) 68.5%
c) 30.8%

#### Work Step by Step

a) Plug in 0 for x into function f.
f(0) = 80$e^{-.5(0)}$+20
Simplify this equation, giving you the answer: 100.
b) Plug in 1 for x into function f.
f(1) = 80$e^{-.5(1)}$+20
Simplfy this equation and round your answer, giving you the answer: $\approx$68.5
c) Plug in 4 for x into function f.
f(4) = 80$e^{-.5(4)}$+20
Simplify this equation and round your answer, giving you the answer: $\approx$30.8