Question

Jude has a deck of playing cards. He is asked to remove one card at random, then a second card. What could Jude do between the events to ensure they are dependent?

Answer 1

Shuffle.

Answer 2

He would have to keep the first card out of the deck before removing the second card.

Explanation:

Two events are dependent if the probability of one event changes based on the result of the other.

To be clear, an action on its own (like drawing a card) is not an event. An event is a possible outcome (or set of outcomes) we could observe.

Since we assume all 52 cards have an equal chance of being drawn on the first pick (that being `1/52`), the only way to change this probability for the second pick is to keep the first card out of the deck. This reduces the size of the deck to 51, meaning each remaining card has a `1/51` chance of being picked—except for the card he drew first, which now has a 0% chance of being drawn again.