Chapter 6: Problem 9
Match each given situation to a possible graph of its density function. Explain. A random number generator is used to choose a real number between 0 and \(100 .\) The random variable \(x\) is the number chosen.
Short Answer
Expert verified
The density function graph is a uniform distribution, represented by a horizontal line from 0 to 100 at height \(\frac{1}{100}\).
Step by step solution
01
Understanding the Problem
In this situation, a random number is chosen between 0 and 100 using a random number generator. The variable \(x\) represents this randomly chosen number. We need to determine the probability density function (PDF) graph that represents this process.
02
Identifying Characteristics of a Uniform Distribution
A uniform distribution is identified when every outcome in a given range has an equal probability of occurring. In this case, since any real number between 0 and 100 is equally likely to be chosen, it suggests a uniform distribution.
03
Considering the Range of the Random Variable
For a random variable \(x\) that is uniformly distributed between 0 and 100, the density function is constant over this interval. The PDF will have a constant height between 0 and 100 on the x-axis.
04
Determining the Height of the Density Function
The total area under the probability density function must equal 1, as it represents the entire probability space. For a uniform distribution between 0 and 100, the height of the PDF is computed as the reciprocal of the interval length: \(\frac{1}{100-0} = \frac{1}{100}\). Hence, the graph should have a constant value of \(\frac{1}{100}\) between 0 and 100.
05
Sketching the Density Function Graph
The graph will be a horizontal line at the height of \(\frac{1}{100}\) extending from \(x=0\) to \(x=100\), indicating that every number between 0 and 100 is equally likely.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Uniform Distribution
A Uniform Distribution is a type of probability distribution where all outcomes are equally probable. It's often visualized as a rectangle on a graph, indicating a constant likelihood over a specified range. For example, when you use a random number generator to pick a number between 0 and 100,
every possible number has the same chance to be selected. This scenario perfectly illustrates a uniform distribution.
The function representing this distribution is a Probability Density Function (PDF), which is flat, signifying uniformity in probability. The PDF of a uniform distribution between 0 and 100 will thus be horizontal, reflecting that no number is given preferential probability over another.
The function representing this distribution is a Probability Density Function (PDF), which is flat, signifying uniformity in probability. The PDF of a uniform distribution between 0 and 100 will thus be horizontal, reflecting that no number is given preferential probability over another.
Random Variable
Simply put, a Random Variable is a numerical value determined by the outcome of a random process. In statistical terms, it's a variable whose possible values are numerical outcomes of a random phenomenon. When you use a random number generator to get a real number between 0 and 100, the chosen number becomes the random variable, denoted by "x."
Random variables can be discrete (specific numbers, like roll outcomes of a die) or continuous (any value in a range, like temperature). For the uniform distribution between 0 and 100, the random variable is continuous, as any number within that range is possible.
Random variables can be discrete (specific numbers, like roll outcomes of a die) or continuous (any value in a range, like temperature). For the uniform distribution between 0 and 100, the random variable is continuous, as any number within that range is possible.
Probability
Probability quantifies how likely an event is to happen. It ranges from 0 (impossible event) to 1 (certain event).
For our uniform distribution example, probability is evenly spread across the range from 0 to 100. You can think of the probability as the area under the PDF curve which is always 1, representing 100%. Each individual real number, however, has a negligible or infinitesimally small probability, but every number collectively makes up the total probability space.
Calculating the probability of selecting a specific number in a continuous range, like 0 to 100, involves understanding the density function instead. Here, the density function helps define the likelihood of x falling within certain intervals.
For our uniform distribution example, probability is evenly spread across the range from 0 to 100. You can think of the probability as the area under the PDF curve which is always 1, representing 100%. Each individual real number, however, has a negligible or infinitesimally small probability, but every number collectively makes up the total probability space.
Calculating the probability of selecting a specific number in a continuous range, like 0 to 100, involves understanding the density function instead. Here, the density function helps define the likelihood of x falling within certain intervals.
Probability Space
Probability Space is a mathematical construct used to model a random process, encompassing all possible outcomes and their probabilities. It consists of three main components:
- Sample Space: all possible outcomes (in our example, any number between 0 to 100).
- Event: any outcome or a set of outcomes of the process.
- Probability Function: a rule assigning probabilities to each event.