Quantitative Techniques COQT111 Unit 3 Quiz

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Questions and Answers

What is a marginal probability?

  • Probability of a single event occurring only (correct)
  • Probability of two events occurring together
  • Probability of multiple outcomes from separate events
  • Probability given that another event has occurred

Which type of probability represents the intersection of two events?

  • Marginal probability
  • Independent probability
  • Joint probability (correct)
  • Conditional probability

How is conditional probability represented mathematically?

  • P(A ∩ B)
  • P(A + B)
  • P(A|B) (correct)
  • P(A - B)

What type of table is typically used to find joint probabilities?

<p>Cross tabulation (B)</p> Signup and view all the answers

In the example given, what is the probability of being female and belonging to blood group O?

<p>0.19 (B)</p> Signup and view all the answers

Which statement correctly defines joint probability?

<p>It represents the probability that two events occur together. (D)</p> Signup and view all the answers

Why is marginal probability called 'marginal'?

<p>It uses values from the margins of a frequency table. (B)</p> Signup and view all the answers

What does conditional probability require?

<p>The occurrence of event B before event A (D)</p> Signup and view all the answers

What is the range of probability values for any event?

<p>0 to 1 (C)</p> Signup and view all the answers

What does a probability of 0 signify?

<p>An event is impossible to occur (C)</p> Signup and view all the answers

What is the sum of probabilities of all possible events in a sample space?

<p>1 (A)</p> Signup and view all the answers

If the probability of event A occurring is 0.6, what is the probability of it not occurring?

<p>0.4 (D)</p> Signup and view all the answers

Which of the following is a property of mutually exclusive events?

<p>They cannot occur at the same time (D)</p> Signup and view all the answers

What is complementary probability?

<p>The probability of an event not occurring (C)</p> Signup and view all the answers

Which of the following defines

<p>Events that cannot occur together (D)</p> Signup and view all the answers

What does it mean for events to be collectively exhaustive?

<p>They cover all possible outcomes (C)</p> Signup and view all the answers

What is the value of $5!$?

<p>120 (C)</p> Signup and view all the answers

How many distinct arrangements can be made with 5 speakers?

<p>120 (A)</p> Signup and view all the answers

In selecting a captain and vice-captain from 5 speakers, how many different pairs can be formed?

<p>20 (C)</p> Signup and view all the answers

Which formula represents the number of permutations of selecting $r$ objects from $n$ objects?

<p>$\frac{n!}{(n-r)!}$ (D)</p> Signup and view all the answers

What distinguishes a permutation from a combination?

<p>Order matters in permutations but not in combinations. (C)</p> Signup and view all the answers

What is the formula for calculating combinations?

<p>$\frac{n!}{r!(n-r)!}$ (C)</p> Signup and view all the answers

If a process has 3 outcomes for event 1 and 4 outcomes for event 2, what is the total number of outcomes?

<p>12 (C)</p> Signup and view all the answers

How many ways can you choose 2 objects from a set of 5 when the order does not matter?

<p>10 (D)</p> Signup and view all the answers

What is the probability of selecting a female from the population?

<p>0.5 (D)</p> Signup and view all the answers

What is the probability that an individual has blood group AB?

<p>0.157 (A)</p> Signup and view all the answers

If events A (Female) and B (Blood group AB) are not mutually exclusive, what is the formula used to find the probability of either event occurring?

<p>P(A ∪ B) = P(A) + P(B) - P(A ∩ B) (D)</p> Signup and view all the answers

What would the probability be if events A (Blood group O) and B (Blood group AB) are mutually exclusive?

<p>0.5140 (B), 0.514 (D)</p> Signup and view all the answers

If the joint probability of events A and B is desired for dependent events, which rule should be applied?

<p>Multiplication rule (A)</p> Signup and view all the answers

What is the correct interpretation of mutually exclusive events?

<p>They cannot occur together in a single trial. (C)</p> Signup and view all the answers

What is the intersection probability for events A (Female) and B (Blood group AB)?

<p>0.0714 (B)</p> Signup and view all the answers

Which of the following statements is TRUE regarding the probability of selecting a person with blood group AB or a female?

<p>P(A ∪ B) = 0.5856 (A)</p> Signup and view all the answers

How many ways can a basketball team of 5 players be chosen from 9 players?

<p>126 (B)</p> Signup and view all the answers

What defines a discrete random variable?

<p>It can take on a finite or countably infinite number of distinct possible values. (B)</p> Signup and view all the answers

Which of the following is an example of a discrete probability distribution?

<p>Number of faulty machines at a company (A)</p> Signup and view all the answers

What is a characteristic of continuous probability distributions?

<p>They take on an infinite number of possible values. (B)</p> Signup and view all the answers

What is a probability distribution?

<p>A list of all possible outcomes and their probabilities. (D)</p> Signup and view all the answers

Which type of probability distribution is classified as continuous?

<p>Normal distribution (A)</p> Signup and view all the answers

Which of the following represents a discrete random variable?

<p>The number of enrolled Engineering students (B)</p> Signup and view all the answers

Which of the following statements is true regarding discrete probability distributions?

<p>Each outcome has a non-zero probability. (B)</p> Signup and view all the answers

What is the characteristics of occurrences in a Poisson process?

<p>They occur uniformly distributed over time. (B)</p> Signup and view all the answers

Which of the following examples is NOT typically modeled as a Poisson process?

<p>The total sales of a store on a holiday. (B)</p> Signup and view all the answers

What does the symbol λ represent in the Poisson probability distribution formula?

<p>The mean number of occurrences of the outcome. (A)</p> Signup and view all the answers

In the Poisson probability distribution, what is the probability of observing 0 occurrences when λ = 1.9?

<p>$P(X = 0) = e^{-1.9} \cdot 1.9^0 / 0!$ (B)</p> Signup and view all the answers

Which statement is true about the occurrences in a Poisson process?

<p>Occurrences can take any integer value from 0 to infinity. (C)</p> Signup and view all the answers

What type of distribution does the number of typographical errors in a dissertation follow?

<p>Poisson Distribution (A)</p> Signup and view all the answers

If λ of a Poisson process is increased, what happens to the probability of observing fewer events?

<p>It decreases. (A)</p> Signup and view all the answers

For the Poisson formula, what does 'e' approximately equal to?

<p>2.71828 (B)</p> Signup and view all the answers

Flashcards

Probability Range

A probability value always lies between 0 and 1, inclusive (i.e. 0 ≤ 𝑃(𝐴) ≤ 1).

Impossible Event

If it is impossible for an event to occur, then 𝑃(𝐴) = 0.

Certain Event

If it is certain that an event will occur, then 𝑃(𝐴) = 1.

Sum of Probabilities

The sum of the probabilities of all possible events in a sample space equals 1 (i.e. for 𝑘 possible events in a sample space, 𝑃(𝐴1 ) + 𝑃(𝐴2 ) + 𝑃(𝐴3 ) + ⋯ + 𝑃(𝐴𝑘 ) = 1).

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Complementary Probability

If 𝑃(𝐴) is the probability of event A occurring, then the probability of event A not occurring (i.e. Ā) is defined as 𝑃(𝐴) = 1 − 𝑃(𝐴).

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Intersection of Events

The intersection of events refers to the occurrence of both events simultaneously.

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Union of Events

The union of events refers to the occurrence of at least one of the events.

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Mutually Exclusive Events

Mutually exclusive events cannot occur simultaneously.

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Marginal probability

The probability of a single event occurring. It's calculated using values on the margins of a frequency table.

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Joint probability

The probability of two or more events happening simultaneously. It's calculated using the value at the intersection of the corresponding rows and columns in a cross-tabulation.

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Conditional probability

The probability of event A happening given that event B has already occurred. It's like event B setting the stage for event A.

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Probability of the Union (Non-Mutually Exclusive Events)

The probability of either event A or event B occurring in a single trial of a random experiment, specifically when events A and B can happen together.

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Conditional Probability (Dependent Events)

The probability of event A occurring given that event B has already happened. This is like event B setting the stage for event A.

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Joint Probability (Dependent Events)

In a single trial of a random experiment, the probability of both event A and event B happening together. This applies when the events are dependent.

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Probability of the Union (Mutually Exclusive Events)

The probability of either event A or B happening in a single trial when they have no overlapping outcomes.

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Multiplication Rule (Dependent Events)

The formula used to find the joint probability of two dependent events occurring together in a single trial of a random experiment.

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Conditional Probability (Independent Events)

The probability of event A not happening when event B is certain to happen. It's like the probability of A when B has already occurred.

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Factorial (n!)

The product of consecutive positive integers from 𝑛 down to 1, denoted as 𝑛!

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Permutation

A way to count the number of ways to arrange a subset of objects from a larger set, where the order of selection matters.

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Permutation Formula (nPr)

The number of different ways to arrange 𝑟 objects from 𝑛 objects when order matters, calculated as 𝑛! / (𝑛 − 𝑟)!

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Combination

A way to count the number of ways to select a subset of objects from a larger set, where the order of selection doesn't matter.

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Combination Formula (nCr)

The number of ways to select 𝑟 objects from 𝑛 objects when order doesn't matter, calculated as 𝑛! / (𝑟! * (𝑛 − 𝑟)!)

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Combined Events Outcome Rule

The total number of outcomes for multiple events is found by multiplying the number of outcomes for each individual event.

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Combined Events Rule Formula

If an event has 𝑛1 possible outcomes, 𝑛2 possible outcomes, etc., the total number of outcomes is 𝑛1 × 𝑛2 × ... × 𝑛𝑗.

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Permutation When All Objects Are Arranged

The number of possible arrangements of objects where order is significant. It's a specific type of permutation where all objects are arranged.

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Combinations Formula

A mathematical formula used to calculate the number of ways to choose r objects from a set of n objects, without regard to order.

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Probability Distribution

A function that assigns probabilities to each possible outcome of a random variable, illustrating the likelihood of different values.

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Discrete Probability Distribution

A probability distribution where the random variable can only take on discrete (often whole number) values.

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Continuous Probability Distribution

A probability distribution where the random variable can take on any value within a continuous range.

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Binomial Probability Distribution

A type of discrete probability distribution that describes the probability of a certain number of successes in a fixed number of trials.

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Poisson Probability Distribution

A type of discrete probability distribution that describes the probability of a certain number of events occurring in a fixed interval of time or space.

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Normal Probability Distribution

A type of continuous probability distribution that is bell-shaped and symmetrical.

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Poisson process

A process where events occur independently and at a constant rate within a given time, space, or volume interval.

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Poisson probability

The probability of a fixed number of events occurring in a specified interval, where the average rate of events is known.

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Lambda (λ) in Poisson

The average number of events that occur in a given time, space, or volume interval.

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Poisson probability distribution formula

The formula used to calculate the probability of observing a specific number of events (x) in a Poisson process, given the average rate (λ).

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Range of x in Poisson

The range of possible values for the number of events (x) in a Poisson process, from zero to infinity.

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Constant 'e' in Poisson

The constant 'e' in the Poisson probability formula, approximately equal to 2.71828.

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P(X = 0) in Poisson

The probability of observing zero events in a given interval.

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Examples of Poisson process

Examples of real-world phenomena that can be modeled using a Poisson process.

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Study Notes

Quantitative Techniques (COQT111) Unit 3: Foundation of Statistical Inference

  • This unit covers the foundations of statistical inference, focusing on probability
  • The unit overview discusses estimating proportions of customers favoring a product via surveys, highlighting the inherent uncertainty in survey results and the importance of calculating likelihoods in management decisions
  • Learning outcomes emphasize calculating probabilities using contingency tables, Poisson and Binomial formulas, including cumulative probabilities

1. Basic Probability Concepts

  • Probability is the likelihood of an event occurring
  • An experiment is a process that yields an outcome
  • Outcomes are results of an experiment
  • An event is a specific outcome or group of outcomes
  • The sample space is the set of all possible outcomes
  • Probability is expressed as a ratio (number of favorable outcomes/total possible outcomes)
  • Probability values range from 0 (impossible) to 1 (certain)

1.1 Types of Probability

  • Subjective probability relies on personal feelings or insights
  • Objective probability uses scientific methods like surveys to determine probabilities

1.2 Properties of Probability

  • Probability values always lie between 0 and 1 (inclusive)
  • If an event is impossible, its probability is 0
  • If an event is certain, its probability is 1
  • The sum of probabilities of all possible outcomes equals 1
  • Complementary probability: The probability of an event not occurring equals 1 minus the probability of the event occurring

1.3 Probability Concepts

  • Intersection: The intersection of events A and B (A ∩ B) includes elements in both A and B
  • Union: The union of events A and B (A ∪ B) includes elements in either A, B, or both
  • Mutually Exclusive: Events that cannot occur together
  • Collectively Exhaustive: Events whose union is the entire sample space

2. Probability Distributions

  • Probability distributions list all possible outcomes and their probabilities
  • Discrete distributions have countable outcomes (e.g., binomial, Poisson)
  • Continuous distributions have uncountable outcomes (e.g., normal)

2.1 Types of Probability Distributions

  • Discrete distributions: Binomial, Poisson
  • Continuous distribution: Normal

2.2 Discrete Probability Distributions

  • Examples: number of enrolled students; faulty machines
  • Each outcome in a discrete distribution has a non-zero probability

2.3 Binomial Probability Distribution

  • Conditions: n trials; two outcomes (success/failure); constant probability of success

2.4 Poisson Probability Distribution

  • Conditions: fixed time/space/volume; independent events; constant average rate of events

3. Unit Summary

  • Summarizes unit content, providing a comprehensive overview of probability concepts, probability distributions, and sampling methods

4. References

  • Lists sources utilized for the unit information

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