A roulette wheel has 36 slots numbered 1-36. Of these slots, the odd numbers are red and the even numbers are black. There are two slots numbered zero, which are green. The croupier spins the wheel, and throws a ball onto the surface; the ball bounces around and ends up in a slot (which is chosen fairly and at random).

a) What is the probability the ball ends up in a green slot?

b) What is the probability the ball ends up in a red slot with an even number?

c) What is the probability the ball ends up in a red slot with a number divisible by 7?