/*! 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 143 Refer to Exercise 3.142 (c). If ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Refer to Exercise 3.142 (c). If the number of phone calls to the fire department, \(Y\), in a day has a Poisson distribution with mean \(5.3,\) what is the most likely number of phone calls to the fire department on any day?

Short Answer

Expert verified
The most likely number of phone calls is 5.

Step by step solution

01

Poisson Distribution Introduction

The Poisson distribution is used to model the number of events occurring within a fixed interval of time or space, given the average number of times the event occurs over that interval. In this case, the event is the number of phone calls to the fire department in a day.
02

Identifying the Distribution Parameters

For a Poisson distribution, the parameter is the average number of events, here denoted as \( \lambda \). In this exercise, \( \lambda = 5.3 \).
03

Understanding Most Likely Number of Calls

The most likely number of phone calls corresponds to the mode of the Poisson distribution, which is the value of \( y \) that maximizes the probability \( P(Y = y) \). For a Poisson distribution, the mode is usually \( \lfloor \lambda \rfloor \) or \( \lfloor \lambda \rfloor -1 \).
04

Floor the Lambda Value

Calculate the floor of \( \lambda \). \( \lfloor 5.3 \rfloor = 5 \). Since \( \lambda \) is not an integer, the most likely number of phone calls can be \( 5 \) or occasionally \( 4 \), but typically it's \( 5 \).
05

Final Decision on Most Likely Number

For practical purposes and given \( \lambda = 5.3 \) is closer to 5, the mode of the distribution and thus the most likely number of calls is \( 5 \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Probability
Probability is a branch of mathematics that deals with the likelihood or chance of different events occurring. It's a way to quantify uncertainty, providing a numerical value between 0 and 1. Here, 0 indicates impossibility, and 1 represents certainty.

In the context of the Poisson distribution, probability helps determine how likely different numbers of phone calls are to be received by the fire department on any given day. This is calculated by using the Poisson probability function, which is generally expressed as:
  • \[ P(Y = y) = \frac{e^{-\lambda} \lambda^y}{y!} \]
Here:
  • \( e \) is the base of the natural logarithms, approximately 2.718.
  • \( \lambda \) is the average number of events (phone calls), here 5.3.
  • \( y \) is the number of phone calls whose probability we want to calculate.
Using this function, you can calculate the likelihood of receiving exactly 0, 1, 2, etc. calls in a day, helping identify the most probable number of calls.
Random Variables
In statistics, a random variable is a numerical outcome of a random process or experiment. It maps outcomes of random processes to numbers, with different results possible each time the process occurs. In the context of the Poisson distribution, the random variable is \( Y \), which represents the number of phone calls received by the fire department in a day.

Random variables can be discrete or continuous. Here, since phone calls can only be whole numbers, \( Y \) is a discrete random variable. It's directly related to actual events and is pivotal in defining the distribution pattern we are studying. Specifically, the number of phone calls can be modeled through Poisson distribution because:
  • The calls occur independently of each other.
  • The average rate of calls is consistent over time.
Understanding \( Y \) as a random variable helps break down the exercise into predictable outcomes using statistical tools, providing clarity in assessing probabilities.
Statistical Modeling
Statistical modeling involves the construction of mathematical models to make predictions or insights about real-world data. The Poisson distribution is a vital tool in statistical modeling, especially for quantifying patterns in count-based data like phone calls, website hits, or arrivals of customers.

In this exercise, statistical modeling is used to examine the number of fire department phone calls, predicted by the Poisson model with an average rate of \( \lambda = 5.3 \). By using this approach:
  • The fire department can allocate resources more effectively, anticipating likely days and times for higher call volumes.
  • City planners can examine patterns over time to identify potential issues that might cause more frequent emergencies.
Modeling such scenarios statistically is crucial for decision-making across various fields, providing a framework to interpret data and predict future occurrences based on past events. This application demonstrates the power of statistical concepts in creating reliable expectations and informed choose actions.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Ten motors are packaged for sale in a certain warehouse. The motors sell for \(\$ 100\) each, but a double-your-money-back guarantee is in effect for any defectives the purchaser may receive. Find the expected net gain for the seller if the probability of any one motor being defective is .08 (Assume that the quality of any one motor is independent of that of the others.)

A store owner has overstocked a certain item and decides to use the following promotion to decrease the supply. The item has a marked price of \(100 .\) For each customer purchasing the item during a particular day, the owner will reduce the price by a factor of one-half. Thus, the first customer will pay \(50\) for the item, the second will pay \(25,\) and so on. Suppose that the number of customers who purchase the item during the day has a Poisson distribution with mean 2 . Find the expected cost of the item at the end of the day. [Hint: The cost at the end of the day is \(100(1 / 2)^{Y}\), where \(Y\) is the number of customers who have purchased the item.]

Show that the hypergeometric probability function approaches the binomial in the limit as \(N \rightarrow \infty\) and \(p=r / N\) remains constant. That is, show that $$\lim _{N \rightarrow \infty} \frac{\left(\begin{array}{l} r \\ y \end{array}\right)\left(\begin{array}{l} N-r \\ n-y \end{array}\right)}{\left(\begin{array}{l} N \\ n \end{array}\right)}=\left(\begin{array}{l} n \\ y \end{array}\right) p^{y} q^{n-y}$$ for \(p=r / N\) constant.

A particular sale involves four items randomly selected from a large lot that is known to contain 10\% defectives. Let \(Y\) denote the number of defectives among the four sold. The purchaser of the items will return the defectives for repair, and the repair cost is given by \(C=3 Y^{2}+Y+2 .\) Find the expected repair cost. [Hint: The result of Theorem 3.6 implies that, for any random variable \(Y\), \(\left.E\left(Y^{2}\right)=\sigma^{2}+\mu^{2} \cdot\right].\)

Many utility companies promote energy conservation by offering discount rates to consumers who keep their energy usage below certain established subsidy standards. A recent EPA report notes that \(70 \%\) of the island residents of Puerto Rico have reduced their electricity usage sufficiently to qualify for discounted rates. If five residential subscribers are randomly selected from San Juan, Puerto Rico, find the probability of each of the following events: a. All five qualify for the favorable rates. b. At least four qualify for the favorable rates.

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.