A Nevada roulette wheel has $38$ slots numbered $00, 0, 1, 2, 3, …, 36$. Eighteen of the numbers $1, 2, …, 36$ are red and $18$ are black; $0$ and $00$ are green.

1. What is the probability of landing on red?

   Answer (a):

   $\frac{9}{4}\approx 47.4$

2. What is the probability of not landing on red?

   Answer (b):

   $\frac{10}{19}=52.6$

3. The bettor put his money on red twice in a row. Use an area or a tree diagram to show how to find the probability that he won both bets.

   Hint (c):