Real-Life Scenarios
Text Version

(Introduction music)

Marissa: In this conditional probability formula, the probability of B given A equals the probability of A and B divided by the probability of A. Doesn’t the  probability of A portion of the numerator and the probability of A in the denominator just divide out?

We know that the probability of A and B is supposed to be the probability of A times the probability of B. This would mean the probability of B given A equals the probability of A and B divided by the probability of A equals the probability of A times the probability of B divided by the probability of A. Thus, the probability of B given A equals the probability of B? Right?

Image description: As Marissa speaks, she points to the probability equations on her clipboard. When she finishes speaking, Allyson takes the clipboard and begins explaining.

Allyson: Only when the events are independent does the probability of A and B equal the probability of A times the probability of B. In our game, gamers can only continue in the game if they meet the first condition. The second event depends on the first happening.

Image description: As Allyson speaks, she points to the probability equations on the clipboard. After she finishes her explanation, Marisa looks confused.