Answer
$P(G~or~F)=\frac{1}{2}=0.5$.
If we play the game 1000 times, we would expect that the metal ball falls into a green slot about 500 times.
Work Step by Step
The sample space S = {0, 00, 1, 2, 3, ..., 34, 35, 36}. So, $N(S)=38$
Let G be the event "00" = {00}. So, $N(G)=1$.
Let F be the event "red slot" = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35}. So, $N(F)=18$.
The events "00" and "red slot" are mutually exclusive (disjoint).
Using the Addition Rule for Disjoint Events (page 270):
$P(G~or~F)=P(G)+P(F)=\frac{N(G)}{N(S)}+\frac{N(F)}{N(S)}=\frac{1}{38}+\frac{18}{38}=\frac{19}{38}=\frac{1}{2}=0.5$
