Question 1

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

Accepted Answer

An outcome or event that cannot be broken down into simpler components.

Question 2

Given three coin tosses, which of the following is NOT a simple event?

Accepted Answer

Getting exactly two heads and one tail.

Question 3

If a procedure has $$n$$ equally likely simple events and event $$A$$ can occur in $$s$$ different ways, what is the classical probability of event $$A$$?

Accepted Answer

$$P(A) = \frac{s}{n}$$

Question 4

A recent year saw 39,000,000 commercial airline flights and 16 crashes. Using the relative frequency approach, what is the probability that a randomly selected flight crashed?

Accepted Answer

$$P = \frac{16}{39,000,000}$$

Question 5

Which of the following statements about the law of large numbers is correct?

Accepted Answer

It states that as a procedure is repeated, the relative frequency probability approaches the actual probability.

Question 6

In a survey, 366 adults said 'yes' to seeing a ghost and 1637 said 'no'. What is the probability that a randomly selected adult said 'yes'?

Accepted Answer

$$P = \frac{366}{2003}$$

Question 7

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

Accepted Answer

All outcomes in which event $$A$$ does not occur.

Question 8

If $$P(A) is $$the probability of event $$A$$, what is the probability of the complement of $$A$$?

Accepted Answer

$$P(A^c) = 1 - P(A)$$

Question 9

A die is rolled once. Which of the following is a simple event?

Accepted Answer

Rolling a 5.

Question 10

Which approach to probability is best used when outcomes are not equally likely and historical data is available?

Accepted Answer

Relative frequency approach.

Question 11

A survey of 2002 adults found that 1782 use the Internet. What is the probability that a randomly selected adult does NOT use the Internet?

Accepted Answer

$$P = \frac{220}{2002}$$

Question 12

Which of the following is NOT a valid probability value?

Accepted Answer

1.2

Question 13

If the probability of an event is 0, what does this mean?

Accepted Answer

The event is impossible.

Question 14

Suppose you flip a coin three times. What is the probability of getting exactly two heads using the classical approach?

Accepted Answer

$$P = \frac{3}{8}$$

Question 15

Which probability approach relies on personal judgment or knowledge of relevant circumstances?

Accepted Answer

Subjective probability.

Question 16

A medical test is repeated many times. According to the law of large numbers, what will happen to the relative frequency probability of a positive result?

Accepted Answer

It will approach the actual probability of a positive result.

Question 17

If you know nothing about the likelihood of different possible outcomes, what should you assume about their probabilities?

Accepted Answer

You should not assume they are equally likely.

Question 18

Which of the following is true about the sample space for three coin tosses?

Accepted Answer

It consists of all possible outcomes that cannot be broken down further.

Question 19

Which probability approach should NOT be used if outcomes are not equally likely?

Accepted Answer

Classical approach.

Question 20

A simple event is defined as:

Accepted Answer

An outcome that cannot be broken down any further.

4.1 Probability – Essentials of Statistics

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