How many red marbles should be added to make this probability 1/3?

The correct answer to this question is 6. This type of question would be found on a math test, related to conditional probability. Due to its difficulty, it could also be found on an IQ test to test one's intellect, as well as an SAT which a high schooler takes before college.

This probability measures the probability that something will happen if another event has already happened. Conditional probability is a critical theory, but it can be challenging to interpret and understand. It is vital for one solving the probability to interpret it correctly to ensure they get the right answer.