1. How many people do there need to be in a room so the there is a greater than 50% chance of at least two of them sharing the same birthday?

2. How many numbers we have to draw from 365 so the there is a greater than 50% chance of at least two of them are the same?

3. How many numbers we have to draw from X so the there is a greater than Y% chance of at least Z of them are the same?

I think X,Y,Z are enough parameters:

Drawing from X=1000 numbers, what is the chance Y that Z=(5,6,7,8...) is the same?

Sorry, I'm not a matematician, just some breakfast ideas ;)

Edit: Inspired by http://datagenetics.com/blog/february72019/index.html