AP Statistics Chapter 15: Probability Rules!

trial

a single attempt or realization of a random phenomenon

disjoint

shares no common outcome

independent

that the outcome of one trial does not influence outcome of another

mutually exclusive

two events that can't occur at the same time with no common outcomes

sample space

collection of all possible outcomes

tree diagram

display of conditional events or probabilities that is helpful in thinking through conditioning

Explain the difference between the Addition Rule for disjoint events and the General Addition Rule

General Addition rule does not require disjoint events? Addition rule (disjoint)- P (A or B) = P(A) + P(B) General Addition Rule- P( A or B) = P(A) + P(B) - P(A and B)

If events A and B are disjoint, then P ( A u B) = P(A) + P(B). If events A and B are NOT disjoint, explain why this formula does not work

If events A and B aren't disjoint, then when you are finding probabilities, you will be counting that probability in the center twice.

In general (whether events are disjoint or not), what is the formula for finding P( A u B)

P (A or B) = P(A) + P(B) - P(A and B)

State the formula for finding conditional probability

P (B/A) = P ( A and B) / P(A)

What is meant by conditional probability

Probability that takes into account a given condition is called conditional probability. P (B/A) "probability of B given A"

event

any set or collection of outcomes

What is meant by joint probability

probability of two different events that are related

conditional probability

probability that takes into account a given condition

outcome

result of a trial