Addition Rules for Probability

What is the range of probability for any event?

The probability of any event will be between 0 and 1, inclusive.

What does a probability of 0 represent?

A probability of 0 indicates that an event will not occur.

What does a probability of 1 represent?

A probability of 1 indicates that an event is certain to occur.

What must the sum of probabilities for a sample space equal?

The sum of probabilities for a sample space must equal 1.

What is the probability of an empty set?

The probability of an empty set, or null set, equals 0.

What is the complement of an event?

The complement of an event is the set of all outcomes in the sample that are not in the event.

How can the probability of an event and its complement be calculated?

The probability of an event is equal to 1 minus the probability of its complement.

What is the addition rule for two events E and F?

The probability that either E or F occurs is: P(E or F) = P(E) + P(F) - P(E and F).

In the deck of cards example, what is the probability of drawing a heart or a queen?

The probability of drawing a heart or a queen is 16 out of 52 or approximately 30.77%.

Why must we subtract the probability of the intersection in the addition rule?

We subtract the probability of the intersection to avoid counting outcomes common to both events twice.