/*! 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 42 BusinessWeek's Corporate Scorebo... [FREE SOLUTION] | 91Ó°ÊÓ

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BusinessWeek's Corporate Scoreboard provides quarterly data on sales, profits, net income, return on equity, price/earnings ratio, and earnings per share for 899 companies (BusinessWeek, August 14,2000 ). The companies can be numbered 1 to 899 in the order they appear on the Corporate Scoreboard list. Begin at the bottom of the second column of random digits in Table \(7.1 .\) Ignoring the first two digits in each group and using three-digit random numbers beginning with \(112,\) read \(u p\) the column to identify the number (from 1 to 899 ) of the first eight companies to be included in a simple random sample.

Short Answer

Expert verified
Identify companies by reading upward from 112 in the random digit table, ensuring all numbers are between 1 and 899.

Step by step solution

01

Understand the Problem

We need to select a simple random sample of 8 companies from a list of 899 companies. We will use a random digit table, starting from a specific location, and generate three-digit numbers to identify these companies.
02

Assign Numbers to Companies

Since there are 899 companies, assign each company a unique number from 001 to 899. This ensures that each company has an equal chance of being selected in the sample.
03

Use Random Digit Table

Begin at the bottom of the second column in Table 7.1. We are instructed to start at the sequence of random digits beginning with 112 and move upwards—this means treating each three-digit group as a potential company number.
04

Select Valid Company Numbers

Read upwards and choose the first eight valid three-digit numbers (from 001 to 899) that appear. Ignore numbers greater than 899 and any duplicates.
05

List the Sampled Companies

Write down the company numbers selected randomly as your simple random sample. Make sure no number is repeated and all numbers are within the valid range (1 to 899).

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Key Concepts

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

Random Digit Table
A Random Digit Table is a tool frequently utilized in statistics to create random samples. It consists of a large matrix filled with single-digit numbers, which are randomly arranged. These tables enable researchers to select samples in a manner that ensures each item has an equal chance of being chosen, thereby minimizing bias.

To use a Random Digit Table effectively, you first need to decide the length of the numbers you need for your sample. For this exercise, since we have 899 companies, you must use three-digit numbers. You then locate a starting point in the digit table, as instructed by the exercise, and begin reading the numbers as needed. Typically, you will skip over any numbers that do not fit your criteria (such as being within your specified range), and you'll also skip any duplicates to maintain sample integrity.

Random Digit Tables are excellent for generating simple random samples because they are both cost-effective and simple to use. They do not require any special equipment or software, making them ideal for quick and reliable sampling techniques.
Sampling Techniques
Sampling techniques are methods used to select a subset or 'sample' from a larger population, to draw conclusions or make inferences about the entire population. There are various sampling techniques, but one of the most straightforward is Simple Random Sampling.

Simple Random Sampling ensures that each member of a population has an equal probability of being included in the sample. By using a random digit table, like in our exercise, you translate this technique into a practical process. This unbiased approach is powerful as it allows statisticians and researchers to avoid skewed results caused by selective sampling.

Other sampling techniques include stratified sampling, cluster sampling, and systematic sampling. Each has its own merits and is chosen based on the specific needs of the research being conducted. However, for broad, uncomplicated application needs, Simple Random Sampling is often the first choice due to its straightforward setup and execution.
Random Number Generation
Random Number Generation is a crucial part of many sampling techniques, especially in simple random sampling. It involves creating a set of numbers that do not follow any specific pattern and have an equal probability of being picked at any time.

There are two most common methods for random number generation: using physical means, like rolling dice or drawing lots, and using mathematical algorithms – either through Random Digit Tables or computer-based programs. In academic and professional settings, the latter is more frequently used due to its efficiency and ability to generate large numbers of truly random numbers swiftly.

When applying Random Number Generation using a Random Digit Table, it works seamlessly with the simple random sampling method, as shown in our exercise. Each three-digit set from the table corresponds to a possible option, ensuring the selection process remains unbiased and effective. In this way, the combination of Random Digit Tables and simple random sampling is a practical approach to conducting research or surveys.

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Most popular questions from this chapter

The Democrat and Chronicle reported that \(25 \%\) of the flights arriving at the San Diego airport during the first five months of 2001 were late (Democrat and Chronicle, July 23 2001 ). Assume the population proportion is \(p=.25\) a. Show the sampling distribution of \(\bar{p},\) the proportion of late flights in a sample of 1000 flights. b. What is the probability that the sample proportion will be within ±.03 of the population proportion if a sample of size 1000 is selected? c. Answer part (b) for a sample of 500 flights.

The mean television viewing time for Americans is 15 hours per week (Money, November 2003 . Suppose a sample of 60 Americans is taken to further investigate viewing habits. Assume the population standard deviation for weekly viewing time is \(\sigma=4\) hours. a. What is the probability the sample mean will be within 1 hour of the population mean? b. What is the probability the sample mean will be within 45 minutes of the population mean?

A population has a mean of 200 and a standard deviation of \(50 .\) Suppose a simple random sample of size 100 is selected and \(\bar{x}\) is used to estimate \(\mu\) a. What is the probability that the sample mean will be within ±5 of the population mean? b. What is the probability that the sample mean will be within ±10 of the population mean?

A market research firm conducts telephone surveys with a \(40 \%\) historical response rate. What is the probability that in a new sample of 400 telephone numbers, at least 150 individuals will cooperate and respond to the questions? In other words, what is the probability that the sample proportion will be at least \(150 / 400=.375 ?\)

The average score for male golfers is 95 and the average score for female golfers is 106 (Golf Digest, April 2006). Use these values as the population means for men and women and assume that the population standard deviation is \(\sigma=14\) strokes for both. A simple random sample of 30 male golfers and another simple random sample of 45 female golfers will be taken. a. Show the sampling distribution of \(\bar{x}\) for male golfers. b. What is the probability that the sample mean is within 3 strokes of the population mean for the sample of male golfers? c. What is the probability that the sample mean is within 3 strokes of the population mean for the sample of female golfers? d. In which case, part (b) or part (c), is the probability of obtaining a sample mean within 3 strokes of the population mean higher? Why?

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