Probability Distributions
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Questions and Answers

What is a necessary condition for a function to be a discrete probability distribution?

  • The probability of each value is 1
  • The sum of the probabilities of all values is -1
  • The sum of the probabilities of all values is 0
  • The probability of each value is between 0 and 1 (correct)
  • What is the formula to calculate the conditional probability P(A|B)?

  • P(A|B) = P(A) × P(B)
  • P(A|B) = P(A ∩ B) + P(B)
  • P(A|B) = P(A) + P(B)
  • P(A|B) = P(A ∩ B) / P(B) (correct)
  • Which of the following is a property of independent events?

  • P(A|B) = P(A) (correct)
  • P(A|B) = 0
  • P(A|B) = P(A) + P(B)
  • P(A|B) = P(A) × P(B)
  • What is the definition of a continuous random variable?

    <p>A variable that takes on an uncountable number of values in a given interval</p> Signup and view all the answers

    What is the expected value of a random variable also known as?

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

    What is the standard deviation of a random variable equal to?

    <p>The square root of the variance</p> Signup and view all the answers

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

    <p>Uniform Distribution</p> Signup and view all the answers

    What is the property of conditional probability that states P(A|B) + P(A'|B) = 1?

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

    What is the sample space when rolling two six-sided dice?

    <p>{(1,1), (1,2), ..., (6,6)}</p> Signup and view all the answers

    For independent events A and B, if P(A) = 0.4 and P(B) = 0.7, what is P(A ∩ B)?

    <p>0.28</p> Signup and view all the answers

    Which type of probability distribution would describe the outcome of a fair six-sided die roll?

    <p>Discrete uniform distribution</p> Signup and view all the answers

    What is the conditional probability, P(A|B), if P(A ∩ B) = 0.2 and P(B) = 0.5?

    <p>0.4</p> Signup and view all the answers

    Which of the following is NOT true for independent events A and B?

    <p>The occurrence of A affects the probability of B</p> Signup and view all the answers

    Which distribution is characterized by a symmetric bell-shaped curve?

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

    Study Notes

    Probability Distributions

    Discrete Probability Distribution:

    • A function that assigns a probability to each possible value of a discrete random variable
    • Must satisfy two conditions:
      1. The probability of each value is between 0 and 1
      2. The sum of the probabilities of all values is 1

    Continuous Probability Distribution:

    • A function that describes the probability of a continuous random variable taking on a given value
    • Examples: Uniform Distribution, Normal Distribution, Exponential Distribution

    Conditional Probability

    Definition:

    • The probability of an event occurring given that another event has occurred
    • Notation: P(A|B) = Probability of event A occurring given that event B has occurred

    Formula:

    • P(A|B) = P(A ∩ B) / P(B)
    • P(A ∩ B) = Probability of both events A and B occurring
    • P(B) = Probability of event B occurring

    Properties:

    • P(A|B) ≥ 0
    • P(A|B) ≤ 1
    • P(A|B) + P(A'|B) = 1 (where A' is the complement of A)

    Independent Events

    Definition:

    • Two events are independent if the occurrence of one event does not affect the probability of the other event
    • Notation: P(A ∩ B) = P(A) × P(B)

    Properties:

    • P(A|B) = P(A) (since the occurrence of B does not affect the probability of A)
    • P(B|A) = P(B) (since the occurrence of A does not affect the probability of B)

    Random Variables

    Definition:

    • A variable whose possible values are determined by chance
    • Can be discrete or continuous

    Types of Random Variables:

    • Discrete Random Variable: Takes on a countable number of distinct values
    • Continuous Random Variable: Takes on an uncountable number of values in a given interval

    Properties:

    • Expected Value (Mean): The long-run average value of a random variable
    • Variance: A measure of the spread or dispersion of a random variable
    • Standard Deviation: The square root of the variance

    Probability Distributions

    • A discrete probability distribution assigns a probability to each possible value of a discrete random variable, satisfying two conditions: probabilities are between 0 and 1, and their sum is 1.
    • A continuous probability distribution describes the probability of a continuous random variable taking on a given value, with examples including Uniform, Normal, and Exponential Distributions.

    Conditional Probability

    • Conditional probability is the probability of an event occurring given that another event has occurred, denoted as P(A|B).
    • Formula: P(A|B) = P(A ∩ B) / P(B), where P(A ∩ B) is the probability of both events A and B occurring, and P(B) is the probability of event B occurring.
    • Properties: P(A|B) ≥ 0, P(A|B) ≤ 1, and P(A|B) + P(A'|B) = 1, where A' is the complement of A.

    Independent Events

    • Two events are independent if the occurrence of one event does not affect the probability of the other event, denoted as P(A ∩ B) = P(A) × P(B).
    • Properties: P(A|B) = P(A), and P(B|A) = P(B), since the occurrence of one event does not affect the probability of the other.

    Random Variables

    • A random variable is a variable whose possible values are determined by chance, and can be discrete or continuous.
    • Types of random variables: discrete random variables take on a countable number of distinct values, while continuous random variables take on an uncountable number of values in a given interval.
    • Properties of random variables: expected value (mean) is the long-run average value, variance measures the spread or dispersion, and standard deviation is the square root of the variance.

    Sample Spaces

    • A sample space is the set of all possible outcomes of an experiment.
    • It is denoted by S or Ω (capital omega).
    • The sample space for tossing a coin is {H, T} (heads or tails).

    Independent Events

    • Independent events are events where the occurrence of one event does not affect the probability of the other event.
    • The probability of both events occurring is the product of their individual probabilities.
    • The formula for independent events is P(A ∩ B) = P(A) × P(B).
    • The probability of getting heads on both coins when tossing two coins is 0.5 × 0.5 = 0.25.

    Probability Distributions

    • A probability distribution is a function that describes the probability of each possible value of a random variable.
    • Probability distributions can be discrete or continuous.
    • Discrete uniform distribution is a type of distribution where each outcome has an equal probability.
    • Binomial distribution models the number of successes in a fixed number of independent trials.
    • Normal distribution (Gaussian distribution) is a continuous distribution with a symmetric bell-shaped curve.

    Conditional Probability

    • Conditional probability is the probability of an event occurring given that another event has occurred.
    • The formula for conditional probability is P(A|B) = P(A ∩ B) / P(B).
    • The probability of drawing a king given that the first card is a king is P(King|King) = P(King ∩ King) / P(King) = 3/4.
    • This is calculated by dividing the probability of drawing two kings (P(King ∩ King) = 3/51) by the probability of drawing a king (P(King) = 4/52).

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    Learn about discrete and continuous probability distributions, their definitions, and examples. Assign probabilities to discrete random variables and understand continuous distributions like Uniform and Normal Distribution.

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