Answer
$P(F)=0.4$
Work Step by Step
The events "green" and "orange" are disjoint (mutually exclusive).
$N(S)=5$
$N(green)=1$
$N(orange)=1$
Using the Addition Rule for Disjoint Events (page 270):
$P(F)=P(green~or~orange)=P(green)+P(orange)=\frac{N(green)}{N(S)}+\frac{N(orange)}{N(S)}=\frac{1}{5}+\frac{1}{5}=\frac{2}{5}=0.4$
