Probability

[mortal flower]

I have no idea how to proceed. Can someone help me?

[reef warren]

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[earnest nexus]

What have you tried?

[mortal flower]

My initial idea was to find the probability of winning in each of the situations. In situation A, it's easier, since theoretically it's 1 in 10 (assuming each person buys 1 ticket). But for situation B, I got a little confused. I thought maybe I could do a combination of 344 choose 9 to find the total number of possibilities (allowing all names to repeat) or maybe a permutation of 344 choose 9. Idk.

[earnest nexus]

Okay, so you know $P(A) + P(\bar A) = 1$, right?

[north crown]

Techie Literate

[mortal flower]

I didn't know. Is it a formula? If so, I don't think I've ever seen it. I might also just be having trouble interpreting it due to the language, I'm a native of Brazil so naturally I speak Portuguese and here the symbols for some quantities are different depending on the textbook used for study.

[mortal flower]

Does it have anything to do with this formula? I saw it on a website.