Question

Again, one big urn with 6 white marbles, 7 black marbles, and 7 red marbles.

Blindfold yourself. Then start picking marbles out and putting them in your pocket.

What's the minimum number of marbles you have to put into your pocket to be certain that at least one of them is black?

Answer 1

[AI-generated answer — Bot GPT 3.5]

To be certain that at least one marble is black, you would need to put all the white and red marbles into your pocket. This would require picking 6 white marbles and 7 red marbles, totaling 13 marbles. Therefore, the minimum number of marbles you have to put into your pocket to be certain that at least one of them is black is 13.