What is the probability that a roulette wheel numbered from

What is the probability that a roulette wheel numbered from 0-36 inclusive, one one spin will:

a. End on an even number b. End on a number divisible by 3 c. End on a prime number d. End on a number between 15 & 21

0-36 are 37 numbers with 19 even and 18 odd

Roulette wheel can end on 37 different numbers

So probability of ending on even number=19/37

Numbers from 0-36 divisible by 3 are:36/3+1=12+1=13

So probability of ending on number divisible by 3=13/37

Prime numbers are:

2,3,5,7,11,13,17,19,23,29,31

SO probability =11/37

Numbers between 15 and 21 are:16,17,18,19,20=5 numbers

Hence probabiliy=5/37