Simple Short Question about Probability: lottery consists of 200 tickets and two prizes. 1st prize ticket is drawn and then, w/o replacement,...

[Dr.Peterson]

You’re basically on the right track, but think about it like this: you bought two tickets out of the 200, so for the first prize draw you have 2 chances in 200, i.e. 2/200=1/1002/200 = 1/1002/200=1/100. That’s why the book says 1/100 for part (a) instead of 1/200 - because either of your two tickets could come up first.

You might want to know that what I've bolded (the same expression appearing three times) suggests that you pasted this from some formatted source. Something similar happens when you hit Reply for a selection here, like this:

2001⋅199198+200198⋅1981≈0.00997

With experience on the site, you will learn how to avoid this sort of thing, and, at the least, to use Preview to see whether what you write will be readable.

I'm a little curious, though, why you would have had to paste this from somewhere else!