A defective bulb from box one is probabilty 100/1000 --> 1/10
A defective bulb from box two is probability 100/2000 --> 1/20

a) 200/3000 --> 2/30
b) Oh God, I hate these questions. Gotta draw bloody diagrams. Gimme a few min.
Ah fuck it. Can't be bothered.

Go with:

a) 2/30
b) 1/30 ???