Probability Chapter 2 Quiz
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Questions and Answers

Classical probability may be categorized under the headings of classical and the relative frequency, or a ______, concept of probability.

posteriori

The probability that the event A will occur is denoted by ______(A).

P

If a random experiment can result in N mutually exclusive and equally likely outcomes, the probability of an event A is defined as the ratio n(A)/______.

N

In relative frequency, if some process is repeated N times and an event with characteristic A occurs n times, the relative frequency is ______/N.

<p>n</p> Signup and view all the answers

When throwing a fair die, there are ______ equally likely outcomes.

<p>6</p> Signup and view all the answers

In the sample space for tossing a coin three times, there are a total of ______ possible sequences.

<p>8</p> Signup and view all the answers

Let A be the event that two or more heads appear ______, and B that all the tosses are the same.

<p>consecutively</p> Signup and view all the answers

Since the outcomes are equally likely and mutually exclusive, the probability of each outcome in the coin toss is ______.

<p>1/8</p> Signup and view all the answers

The possible outcomes when tossing a coin are heads (denoted by H) and ______ (denoted by T).

<p>tails</p> Signup and view all the answers

The set of all possible outcomes of an experiment is called the ______ Space.

<p>Sample</p> Signup and view all the answers

When two coins are tossed, the sample space can be represented as S = { HH , HT , ______ , TT }.

<p>TH</p> Signup and view all the answers

The outcomes of two tossed coins can also be represented as ordered pairs of 1 and ______.

<p>0</p> Signup and view all the answers

When a coin is tossed three times, the sample space consists of ______ outcomes.

<p>8</p> Signup and view all the answers

If a coin is tossed repeatedly until a ______ occurs, the sample space is given as S = {H, TH, TTH...}.

<p>head</p> Signup and view all the answers

A possible sample space for the number of tosses required to obtain a head would be the set of all positive ______.

<p>integers</p> Signup and view all the answers

In a scenario where a light bulb is measured until it burns out, the ______ of operation is assessed.

<p>time</p> Signup and view all the answers

If D1 is the event that the first fuse is defective, then P ( D1 ) = ____

<p>5/20</p> Signup and view all the answers

The events B1, B2,..., Bk constitute a _______ of the sample space S.

<p>partition</p> Signup and view all the answers

To find the probability of occurrence of an event A that can occur with one of the B's events, the rule of _____ probability is required.

<p>total</p> Signup and view all the answers

If P(Bi) > 0 for i = 1, 2,..., k, then for any event A in S, P ( A ) = ____ P ( Bi ).P ( A/ Bi ).

<p>∑</p> Signup and view all the answers

The formula used for the probability of the intersection of events D1, D2, and D3 is P( D1  D2  D3 ) = ____.

<p>5/20 x 4/19 x 3/18</p> Signup and view all the answers

Since the events B1, B2,..., Bk are exhaustive, their union equals ____.

<p>S</p> Signup and view all the answers

A = A ∩ S = (A ∩ B1) ∪ (A ∩ B2) ∪...∪ (A ∩ Bk) is a representation of ____ events.

<p>exhaustive</p> Signup and view all the answers

A ∩ B1, A ∩ B2, ..., A ∩ Bk are also mutually ____.

<p>exclusive</p> Signup and view all the answers

The sample space for the experiment of tossing a fair die twice is denoted by ______.

<p>S</p> Signup and view all the answers

The probability of event A is denoted by P(A) and follows the axioms of probability, starting with Axiom I: P(A) ≥ ______.

<p>0</p> Signup and view all the answers

The events A1 and A2 in the example correspond to { ______ number greater than 5 } and { an odd number less than 9 }, respectively.

<p>prime</p> Signup and view all the answers

In the example, event A consists of the outcomes {(3, 6), (4, 5), (5, 4), (6, ______)}.

<p>3</p> Signup and view all the answers

For events A1 and A2, the total number of possible outcomes in the sample space is denoted by ______.

<p>N</p> Signup and view all the answers

If n(A) = 3, then P(A) can be calculated as P(A) = n(A) / ______.

<p>N</p> Signup and view all the answers

There are a total of ______ outcomes when tossing a fair die twice.

<p>36</p> Signup and view all the answers

According to Axiom II: P(S) must equal ______.

<p>1</p> Signup and view all the answers

The eight possible outcomes from flipping a fair coin are HHH, HHT, HTH, THH, HTT, THT, TTH, and ______.

<p>TTT</p> Signup and view all the answers

Event A includes the outcomes {HHH, ______}

<p>HHT</p> Signup and view all the answers

The intersection of events A and B is ______.

<p>HHT</p> Signup and view all the answers

The probability of event A is P(A) = ______.

<p>1/4</p> Signup and view all the answers

Theorem 2.10 states that if events A and B are independent, then A and ______ are also independent.

<p>B</p> Signup and view all the answers

To define independence for multiple events, we consider the probability of the intersection of any ______ of these events.

<p>k</p> Signup and view all the answers

For three events A, B, and C to be independent, the equation P(A ∩ B ∩ C) must equal P(A) · P(B) · ______.

<p>P(C)</p> Signup and view all the answers

Events can be pairwise independent without being completely ______.

<p>independent</p> Signup and view all the answers

Two events A and B are said to be ______ if the occurrence or nonoccurrence of either one does not affect the probability of the occurrence of the other.

<p>independent</p> Signup and view all the answers

If two events A and B are independent, then P(B / A) = P(______).

<p>B</p> Signup and view all the answers

The formal definition of independence states that two events A and B are independent iff P(A ∩ B) = P(A) P(______).

<p>B</p> Signup and view all the answers

In Bayes' formula, we can find P(B2 / A) using the formula P(B2) P(A / ______) / P(A).

<p>B2</p> Signup and view all the answers

The tree diagram describes the process and gives the probability of each ______ of the tree.

<p>branch</p> Signup and view all the answers

Events A and B are dependent if the occurrence of one affects the ______ of the other.

<p>probability</p> Signup and view all the answers

If A is the event of getting heads on the first two tosses and B is the event of getting tails on the third toss, A and B are ______.

<p>independent</p> Signup and view all the answers

In the example of tossing a fair coin three times, for events A and B to be independent, the occurrence of ______ must not influence the occurrence of the other.

<p>C</p> Signup and view all the answers

Flashcards

Sample Space

The set of all possible outcomes of a random experiment.

Outcome

A single trial of a random experiment. It can be a specific outcome like heads (H) or tails (T) when flipping a coin.

Random Experiment

Represents an experiment that has a number of possible outcomes. It can be something as simple as flipping a coin or a more complex experiment like rolling a die.

Sample Space

A collection of outcomes from a random experiment. Each outcome is unique and cannot be repeated.

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Sample Space Example 1

In a coin toss where we're interested in whether it's heads (H) or tails (T), the Sample Space would be {H, T}.

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Sample Space Example 2

If we toss 2 coins and want to know all the possible combinations of heads (H) and tails (T), the Sample Space would be {HH, HT, TH, TT}.

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Sample Space Example 3

In a coin toss experiment where we repeat until a head appears, the Sample Space is infinite. This is because we could theoretically keep getting tails indefinitely.

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Sample Space Example 4

If we are only interested in the total number of heads from flipping 2 coins, the Sample Space would be {0, 1, 2}. This is because we could get 0, 1, or 2 heads.

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Classical Probability

A type of probability based on logical reasoning and equal likelihood of outcomes. It's used when we have complete knowledge of the possible outcomes and their chances of occurring.

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Mutually Exclusive Events

Events that cannot occur at the same time in an experiment.

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Classical Probability Formula

The probability of an event is the ratio of the number of outcomes favorable to the event to the total number of possible outcomes.

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Relative Frequency Probability

A type of probability that depends on observing repeated events and analyzing the frequency of a specific outcome. It relies on real-world data.

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Relative Frequency

The proportion of times an outcome occurs compared to the total number of trials. It gives an estimate of the probability.

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Repeated Trials

The process of repeating an experiment multiple times to observe the frequency of a specific outcome.

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Trial

A single instance of an experiment.

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Conditional Probability

The probability of an event occurring given that another event has already occurred.

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Partition of Sample Space

A set of events that are mutually exclusive and their union covers the entire sample space. This means that one and only one of these events must occur.

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Law of Total Probability

A formula that calculates the probability of an event A occurring given that any one of the events B1, B2, ... Bk, which form a partition of the sample space, has already occurred. It is the sum of the probabilities of A occurring under each of the Bi events.

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Joint Probability

A probability that involves the intersection of two or more events. It represents the probability of all those events happening together.

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Bayes' Theorem

A formula used to calculate the probability of an event A occurring given that another event B has already occurred.

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Chain Rule of Probability

A process of repeatedly multiplying probabilities to find the probability of a sequence of events.

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Independent Events

Indicates that the occurrence of one event does not impact the probability of another event occurring. Events are considered independent if the probability of one event happening does not depend on whether or not the other event has occurred.

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Dependent Events

The opposite of independent events. The occurrence of one event impacts the probability of another event occurring.

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Probability of an event

The probability of an event is the number of favorable outcomes divided by the total number of possible outcomes. For example, if you flip a coin, there are two possible outcomes (heads or tails) and one favorable outcome (heads). The probability of flipping heads is 1/2.

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Probability of an event (formula)

The probability of an event A occurring is the number of favorable outcomes for A divided by the total number of outcomes in the sample space.

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Intersection of events (A ∩ B)

The intersection of two events A and B is the set of outcomes that belong to both A and B. The notation for this is A ∩ B or A intersection B.

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Union of events (A ∪ B)

The union of two events A and B is the set of outcomes that belong to either A or B or both. The notation for this is A ∪ B or A union B.

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Probability of union of events

The probability of the union of two events A and B is the probability of A plus the probability of B minus the probability of the intersection of A and B. This is represented as: P(A ∪ B) = P(A) + P(B) - P(A ∩ B).

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Fair die

A fair die is a die where each face has an equal probability of landing.

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Axiomatic approach to probability

Axiomatic approach to probability defines probability using axioms that hold true for any probability measure. The axioms are: (1) non-negativity (probability is never negative), (2) normalization (probability of the sample space is 1), and (3) additivity (probability of the union of disjoint events is the sum of their probabilities).

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Probability Formula for Independent Events

The probability of the intersection of two independent events is equal to the product of their individual probabilities.

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Tree Diagram

A visual representation of events and their probabilities, branching out to show possible outcomes and their likelihoods.

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Bayes' Formula

A formula used to calculate the probability of a specific event (A) happening given that another event (B) has already occurred.

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Independence Test

A way to determine if two events are independent based on their conditional probabilities.

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Probability Formula

The probability of an event happening is calculated by dividing the number of favorable outcomes by the total number of possible outcomes.

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Product Rule for Independent Events

The probability of the intersection of two events is equal to the product of their individual probabilities if and only if the events are independent.

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Sum Rule for Two Events

The probability of the union of two events is the sum of their individual probabilities minus the probability of their intersection.

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Independence of Events

If one event does not affect the probability of another event happening, then they are independent.

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Study Notes

Chapter 2: Probability

  • Probability theory originated in gambling in the 18th century and has since expanded into various fields.
  • Probability is frequently used in communication, as seen in medical prognoses (e.g., 50-50 chance).
  • Probability is a number between 0 and 1, indicating likelihood. Closer to 1 = more likely; closer to 0 = less likely; An event that's impossible = 0; a certain event = 1.

Basic Definitions

  • Experiment: A process that yields an observable outcome. A trial is one performance of the experiment.
  • Outcome: The specific result of an experiment.
  • Sample Space (S): The set of all possible outcomes of a random experiment. One and only one outcome will occur on any given trial of an experiment.

Example 2.1

  • An experiment of tossing two coins has possible outcomes recorded as a sample space: {HH, HT, TH, TT}

Example 2.2

  • If tossing a coin until a head appears then the sample space could be positive integers: {1, 2, 3...}

Example 2.3

  • A sample space for a light bulb's lifespan could be nonnegative real numbers (e.g., time in hours).
  • The time being measured only to the nearest hour: {0, 1, 2, 3...}

Sample Space

  • Finite: Consists of a finite number of outcomes.
  • Discrete: Finite or countably infinite (can be put into one-to-one correspondence with the positive integers)
  • Countably Infinite: Has a infinite number of outcomes that can be counted.
  • Continuous: Contains an uncountable infinite number of outcomes (represented by a continuum, such as all points on a line).

Event

  • A subset of the sample space. Events can consist of more than one outcome

Occurrence of an Event

  • An event has occurred if the outcome of the experiment belongs to the set defining the event.

Intersection of Events (A∩B)

  • The outcomes that belong to both event A and event B.

Mutually Exclusive Events

  • Two events that cannot occur at the same time.

Complementary Event (A’)

  • The set of outcomes not in event A . 

Equally Likely Events

  • Outcomes of a random experiment that have the same chance of occurring.

Classical Probability

  • Probability understood in terms of the ratio of favorable outcomes to possible outcomes (if each outcome is equally likely).
  • The formula: P(A) = n(A)/n(S), where n(A) is the number of favorable outcomes and n(S) is the total number of possible outcomes.
    • Outcomes must be mutually exclusive and equally likely

Examples of Probability Calculations

  • Examples are provided demonstrating calculations for events involving dice rolls, coin flips, and other scenarios.

Axiomatic Approach to Probability

  • Probability defined using three axioms:
    • P(A) >= 0 for all events A.
    • P(S) = 1, where S is the sample space.
    • If A1, A2, A3,... is a sequence of mutually exclusive events, then P(A1∪A2∪A3...) = P(A1) + P(A2) + P(A3) + ...

Conditional Probability

  • Probability of an event given another event has occurred.
  • P(B/A) = P(A∩B) / P(A)

Multiplication Rule

  • If events A and B are independent, P(A∩B) = P(A)*P(B)

Total Probability

  • P(A) = Σ [P(Bi) * P(A/Bi)], where the Bi form a partition of the sample space.

Bayes' Theorem

  • Calculating the probability of an event occurring given some conditions.
  • P(B/A) = [P(B).P(A/B)] / P(A)

Independent Events

  • Two events are independent if the occurrence of one does not affect the probability of the other.

Other Theorems and Rules

  • Various theorems and rules are introduced for calculating probabilities of different types of events (e.g., the addition rule for events if they are not mutually exclusive)

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Probability - Chapter 2 PDF

Description

Test your understanding of probability concepts as introduced in Chapter 2. This quiz covers essential definitions, experiments, and sample spaces, providing a solid foundation in probability theory. Enhance your grasp of likelihoods and outcomes with practical examples.

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