/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 15 Verify that the following functi... [FREE SOLUTION] | 91Ó°ÊÓ

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Verify that the following functions are probability mass functions, and determine the requested probabilities. $$ \begin{array}{l|c|c|c|c|c} x & -2 & -1 & 0 & 1 & 2 \\ \hline f(x) & 1 / 8 & 2 / 8 & 2 / 8 & 2 / 8 & 1 / 8 \end{array} $$ (a) \(P(X \leq 2)\) (b) \(P(X>-2)\) (c) \(P(-1 \leq X \leq 1)\) (d) \(P(X \leq-1\) or \(X=2)\)

Short Answer

Expert verified
The function is a valid PMF. (a) 1, (b) \(\frac{7}{8}\), (c) \(\frac{3}{4}\), (d) \(\frac{1}{2}\).

Step by step solution

01

Verify Probability Mass Function

A probability mass function (PMF) must satisfy two conditions: each probability must be between 0 and 1, and the sum of all probabilities must be equal to 1. Check these for the given function:1. Each probability: \( \frac{1}{8}, \frac{2}{8}, \frac{2}{8}, \frac{2}{8}, \frac{1}{8} \) are all between 0 and 1.2. Sum \(= \frac{1}{8} + \frac{2}{8} + \frac{2}{8} + \frac{2}{8} + \frac{1}{8} = \frac{8}{8} = 1\).Thus, the given function is a valid PMF.
02

Calculate \(P(X \leq 2)\)

Since \(P(X \leq 2)\) includes all possible outcomes, we sum all probabilities:\( P(X \leq 2) = \frac{1}{8} + \frac{2}{8} + \frac{2}{8} + \frac{2}{8} + \frac{1}{8} = 1 \).
03

Calculate \(P(X > -2)\)

To find \(P(X > -2)\), sum the probabilities for \(x = -1, 0, 1, 2\):\( P(X > -2) = \frac{2}{8} + \frac{2}{8} + \frac{2}{8} + \frac{1}{8} = \frac{7}{8} \).
04

Calculate \(P(-1 \leq X \leq 1)\)

The probability for \(-1 \leq X \leq 1\) includes \(x = -1, 0, 1\):\( P(-1 \leq X \leq 1) = \frac{2}{8} + \frac{2}{8} + \frac{2}{8} = \frac{6}{8} = \frac{3}{4} \).
05

Calculate \(P(X \leq -1 \text{ or } X = 2)\)

This probability includes \(x = -2, -1, 2\):\( P(X \leq -1 \text{ or } X = 2) = \frac{1}{8} + \frac{2}{8} + \frac{1}{8} = \frac{4}{8} = \frac{1}{2} \).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Discrete Probability
In the realm of probability, discrete probability is a fundamental concept studied through distinct, separate events with specific outcomes.
Think of it as counting possible outcomes like rolling a die or drawing a card. Each outcome in a discrete probability must be clear and countable.

For instance, the exercise we have involves a probability mass function (PMF) over a discrete set of values: \(-2, -1, 0, 1,\) and \(2\). Here, each value is independent and does not blur into fractions or decimals because they are distinct.
This makes it essential for the values in our problem to be whole numbers, each assigned a specific probability.
  • Counting outcomes: Each distinct number \(-2, -1, 0, 1,\) and \(2\) are outcomes we consider in discrete probability.
  • Assigning probabilities: Each of these numbers has a probability assigned, which forms the base requirement of our problem.
Probability Calculation
Calculating probabilities in any scenario involves straightforward arithmetic, especially in discrete cases as seen in our problem.
Let's explore some probability calculations with the given PMF:

* When computing \(P(X \leq 2)\), we calculate the probability that the random variable \(X\) is less than or equal to 2. In the exercise, this involved summing all given probabilities, leading to the answer of \(1\).

* Calculating \(P(X > -2)\) involved finding probabilities for all outcomes greater than \(-2\). This meant adding probabilities for \(-1, 0, 1,\) and \(2\), resulting in \(\frac{7}{8}\).

Continuous learning on probability calculation involves understanding how to select and sum specific probabilities based on given conditions.
It's a powerful tool to predict the likelihood of varying scenarios using basic addition and reasoning.
Probability Distribution
The concept of distribution refers to how probabilities are spread over different outcomes. In our exercise, we use a probability mass function, which is a type of probability distribution.
This specific distribution helps us determine how likely each discrete outcome is.

The PMF assigns each possible outcome of a discrete random variable a probability, ensuring that:
  • Each individual probability is a value between 0 and 1.
  • The sum of all probabilities equals 1, confirming all possible outcomes are accounted for.

In our exercise, the outcomes with probabilities are organized into a tabular format for clarity: * \(-2\), \(-1\), \(0\), \(1\), and \(2\) with probabilities \(\frac{1}{8}, \frac{2}{8}, \frac{2}{8}, \frac{2}{8}, \frac{1}{8}\) respectively.

Using this distribution method allows us to quickly determine probabilities for various queries, such as less than, greater than, or within a range of outcomes.
Statistical Analysis
Statistical analysis involves interpreting data and extracting meaningful insights, using various mathematical tools and techniques.
In our exercise, statistical analysis allows us to verify that a given function conforms to being a probability mass function by ensuring specific conditions are met.

Let's break it down:
* Verification phase: The exercise starts by confirming each probability is between 0 and 1, and they collectively sum to 1. This is a foundational check for any PMF.* Evaluating probabilities: We further interpret scenarios like \(X \leq -1\) or \(X = 2\) through calculated probabilities. In this exercise, statistical analysis gives us consistent and reliable probabilities, like \(\frac{1}{2}\) for this particular situation.

Overall, using statistical analysis in probability requires observing and calculating carefully, ensuring all possible outcomes are addressed while adhering to probability principles.

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Most popular questions from this chapter

The number of surface flaws in plastic panels used in the interior of automobiles has a Poisson distribution with a mean of 0.05 flaw per square foot of plastic panel. Assume an automobile interior contains 10 square feet of plastic panel. (a) What is the probability that there are no surface flaws in an auto's interior? (b) If 10 cars are sold to a rental company, what is the probability that none of the 10 cars has any surface flaws? (c) If 10 cars are sold to a rental company, what is the probability that at most one car has any surface flaws?

A batch contains 36 bacteria cells and 12 of the cells are not capable of cellular replication. Suppose you examine three bacteria cells selected at random, without replacement. (a) What is the probability mass function of the number of cells in the sample that can replicate? (b) What are the mean and variance of the number of cells in the sample that can replicate? (c) What is the probability that at least one of the selected cells cannot replicate?

The number of failures of a testing instrument from contamination particles on the product is a Poisson random variable with a mean of 0.02 failure per hour. (a) What is the probability that the instrument does not fail in an eight-hour shift? (b) What is the probability of at least one failure in a 24 -hour day?

The number of views of a page on a Web site follows a Poisson distribution with a mean of 1.5 per minute. (a) What is the probability of no views in a minute? (b) What is the probability of two or fewer views in 10 minutes? (c) Does the answer to the previous part depend on whether the 10 -minute period is an uninterrupted interval? Explain.

Suppose that the number of customers who enter a bank in an hour is a Poisson random variable, and suppose that \(P(X=0)=0.05 .\) Determine the mean and variance of \(X .\)

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