$$P(A \text{ or } B) = P(A) + P(B)$$

$$P(A \text{ or } B) = P(A) + P(B) - P(A \text{ and } B)$$

Probability calculated as $$\frac{\text{number of times event occurs}}{\text{total number of trials}}$$

Question 1

Which of the following best describes a 'simple event' in probability?

Accepted Answer

An event that consists of exactly one outcome.

Question 2

Given a fair six-sided die, what is the classical probability of rolling a 4?

Accepted Answer

$$\frac{1}{6}$$

Question 3

If event $$A$$ and event $$B$$ are mutually exclusive, which formula correctly calculates $$P(A 	ext{ or } B)$$?

Accepted Answer

$$P(A 	ext{ or } B) = P(A) + P(B)$$

Question 4

Which of the following is the correct definition of the complement of event $$A$$?

Accepted Answer

All outcomes that are not in $$A.$$

Question 5

If $$P(A) = 0.3$$, what is $$P(\overline{A})$$?

Accepted Answer

$$0.7$$

Question 6

A weather forecaster estimates a 70% chance of rain tomorrow. This is an example of which type of probability?

Accepted Answer

Subjective probability

Question 7

If the odds in favor of an event are $$3:2$$, what is the probability of the event?

Accepted Answer

$$\frac{3}{5}$$

Question 8

A bag contains 5 red, 3 blue, and 2 green marbles. If one marble is drawn at random, what is the probability it is blue?

Accepted Answer

$$\frac{3}{10}$$

Question 9

Which formula represents the addition rule for any two events $$A$$ and $$B$$?

Accepted Answer

$$P(A 	ext{ or } B) = P(A) + P(B) - P(A 	ext{ and } B)$$

Question 10

If $$P(A) = 0.4$$, $$P(B) = 0.5$$, and $$P(A 	ext{ and } B) = 0.2$$, what is $$P(A 	ext{ or } B)$$?

Accepted Answer

$$0.9$$

Question 11

Which of the following best describes 'relative frequency probability'?

Accepted Answer

Probability calculated as $$\frac{	ext{number of times event occurs}}{	ext{total number of trials}}$$

Question 12

If the odds against an event are $$4:1$$, what is the probability of the event?

Accepted Answer

$$\frac{1}{5}$$

Question 13

A coin is flipped 100 times and lands on heads 56 times. What is the relative frequency probability of getting heads?

Accepted Answer

$$0.56$$

Question 14

Which of the following is NOT a requirement for classical probability?

Accepted Answer

Probabilities must be based on observed data.

Question 15

If $$P(A) = 0.6$$ and $$P(B) = 0.3$$, and $$A$$ and $$B$$ are mutually exclusive, what is $$P(A 	ext{ or } B)$$?

Accepted Answer

$$0.9$$

Question 16

Which of the following is an example of a compound event?

Accepted Answer

Drawing a red card or a king from a deck of cards.

Question 17

If $$P(A) = 0.5$$ and $$P(B) = 0.4$$, and $$P(A 	ext{ and } B) = 0.2$$, what is $$P(A 	ext{ or } B)$$?

Accepted Answer

$$0.7$$

Question 18

Which of the following best describes the addition rule for probability?

Accepted Answer

It is used to find the probability of either of two events occurring.

Probability: Definitions, Types, Complements, Odds, and Addition Rule

Study Guide - Practice Questions