Probability

Question 1

What is an experiment?

Answer 1

A repeatable process that gives outcomes

Question 2

What is an event?

Answer 2

A collection of one (or more) outcomes.

Question 3

What is a sample space?

Answer 3

The set of all possible outcomes in an experiment.

Question 4

What is the probability of an event occurring? P(event occurring)

Answer 4

P(event occurring) = No. outcomes in that event / Total possible outcomes

Question 5

What is the probability of an impossible event?

Answer 5

Zero.

Question 6

What is the probability of a certain event?

Answer 6

One.

Question 7

What is conditional probability?

Answer 7

Where the probability of an event is affected by whether another event has already occurred or not.

Question 8

What is the addition rule?

Answer 8

P(A U B) = P(A) + P(B) - P(A n B)

This formula can be rearranged to find P(A n B)

Question 9

What kind of probability do tree diagrams represent?

Answer 9

Conditional probabilities

Question 10

What is a mutually exclusive event?

Answer 10

• When two events cannot happen at the same time.
• there is no intersection (separate venn circles)
• P(A n B) = 0
• The addition rule =>
  P(A U B) = P(A) + P(B)

Question 11

What is an independent event?

Answer 11

• When one event has no effect on another.
• P(A | B) = P(A)
• The multiplication rule* =>
  P( A n B) = P(A) x P(B)

*As P(A | B) = P(A n B)/ P(B);
P(A n B) = P(B) x P(A | B)