W (9), X (1), Y (9), Z (1)

General chance of being in either group: 50% (10 people with autism, 10 with ADHD, 20 total).

Chance of having autism if you have ADHD: 50% (9 with autism, 9 without, 10 total).

Chance of having ADHD if you have autism: 90% (9 with ADHD, 9 without, 10 total).