Question

What does conditional probability mean?

• A. The probability of an event ( A ), given that another ( B ) will not occurred.
• B. The probability of events A and B occuring together.
• C. The probability of an event ( A ), given that another ( B ) has already occurred.
• D. None of these

Answer 1

Answer: (C)

The probability of an event ( A ), given that another ( B ) has already occurred.

Conditional probability is a measure of the probability of an event given that another event has occurred.

If the event of interest is $A$ and the event $B$ is known or assumed to have occurred, "the conditional probability $A$ of given $B$'', is usually written as $P\left(A|B\right)$.

Thus conditional probability means, the probability of an event $A$ given that another $B$ has already occurred.

Therefore option $\left(C\right)$ is correct.