Could someone please work out the probability of winning a raffle prize under the following circumstances? It's a friendly argument/debate I'm try to settle! Please show workings in any answers.

I have bought one ball in a raffle competition. There are 80 people taking part, so 80 balls in the raffle machine. The thirst three balls drawn out from the raffle win a prize (in descending monetary value with each ball drawn).

I presume the probability of me winning the first prize is 1/80, second prize, 1/79, and third prize 1/78.

What I want to know is firstly, is my above presumption correct? And secondly, what is the probability of me winningof the three prizes?any

If you could show your working in the answers you post please?

Much appreciated!