Okay, I'm having trouble understanding the difference between "and" and "or" in problems.

Question

For example:
-When drawing a single card, find the probability of getting a 4 OR a diamond.
-When drawing a single card, find the probability of getting a jack AND a black card.

What is the difference? What are the answers to these so I can check my study guide? Please help, I have a test soon!

Answer 1

When the problem states OR -- then you need to figure two different probabilities.

You have a 1 in 13 chance of drawing a 4. You have a 1 in 4 chance of drawing a diamond.

Answer 2

For either-or probabilities, you add the individual probabilities. 4/52 + 13/52 - 1/52 = ?

Subtract the 1/52, because one of the fours is a diamond.

There are two black jacks in the deck. 2/52 = 1/26

To determine probabilities of all events occurring, multiply the individual probabilities.