Question 1

Which of the following best describes a subjective probability?

Accepted Answer

A probability representing someone's personal degree of belief.

Question 2

Suppose you roll a fair six-sided die. What is the theoretical probability of rolling a number greater than 4?

Accepted Answer

$$\frac{1}{3}$$

Question 3

If $$P(A) = 0.4$$ and $$P(B) = 0.5$$, and A and B are disjoint events, what is $$P(A \cup B)$$?

Accepted Answer

$$0.9$$

Question 4

Which of the following is NOT a requirement for a legitimate probability assignment?

Accepted Answer

Probabilities can be negative if the event is unlikely.

Question 5

If $$P(A) = 0.3$$, what is the probability of the complement of A, $$P(A^c)$$?

Accepted Answer

$$0.7$$

Question 6

Two events A and B are independent. If $$P(A) = 0.6$$ and $$P(B) = 0.5$$, what is $$P(A \cap B)$$?

Accepted Answer

$$0.3$$

Question 7

Which rule would you use to find the probability that at least one of two disjoint events occurs?

Accepted Answer

Addition Rule

Question 8

If events A and B are disjoint, which of the following statements is true?

Accepted Answer

$$P(A \cap B) = 0$$

Question 9

A medical test for a rare disease has a 99% chance of correctly identifying a sick patient (true positive) and a 95% chance of correctly identifying a healthy patient (true negative). If 1% of the population has the disease, what type of probability is being described by the 99% and 95% values?

Accepted Answer

Empirical probability

Question 10

If $$P(A) = 0.2$$ and $$P(B) = 0.5$$, and A and B are independent, what is $$P(A \cup B)$$?

Accepted Answer

$$0.6$$

Question 11

A weather forecaster says there is a 70% chance of rain tomorrow. This is an example of:

Accepted Answer

Subjective probability

Question 12

If $$P(A) = 0.4$$ and $$P(B) = 0.3$$, and A and B are disjoint, what is $$P(A \cap B)$$?

Accepted Answer

$$0$$

Question 13

Which of the following best describes the complement rule?

Accepted Answer

The probability of an event not occurring is 1 minus the probability that it does occur.

Question 14

A legitimate probability assignment must satisfy which of the following?

Accepted Answer

Each probability is greater than or equal to 0 and less than or equal to 1.

Question 15

If $$P(A) = 0.25$$, what is $$P(A^c)$$?

Accepted Answer

$$0.75$$

Question 16

Which of the following statements about independent events is correct?

Accepted Answer

If A and B are independent, $$P(A \cap B) = P(A) \cdot P(B).$$

Question 17

A bag contains 3 red balls and 7 blue balls. If one ball is drawn at random, what is the theoretical probability it is red?

Accepted Answer

$$0.3$$

Question 18

If $$P(A) = 0.5$$ and $$P(B) = 0.4$$, and A and B are independent, what is $$P(A \cap B^c)$$?

Accepted Answer

$$0.2$$

Question 19

Which of the following is an example of disjoint (mutually exclusive) events?

Accepted Answer

Rolling a 2 and rolling a 5 on a single die roll.

Question 20

If $$P(A) = 0.6$$ and $$P(B) = 0.3$$, and A and B are disjoint, what is $$P(A \cup B)$$?

Accepted Answer

$$0.9$$

Fundamental Probability Rules and Concepts

Study Guide - Practice Questions

Study Guide - Flashcards