You have an interesting deck of cards:

Question

there are an unknown number of different types of cards,
each card type is repeated many times (let's say infinitely),

if these cards are placed face down, how many must you flip over before you are fairly confident you have found all the different types of card in the deck?

Answer 1

"Unknown number of different types" lead to unknown answer.

Answer 2

I'm not sure how to interpret the answer above...

let's say there are 6 different types of cards and an infinite number of each type,

how many cards do you need to look at to be 95% confident there are not 7 different types?