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You need to select a simple random sample of four from eight friends who will participate in a survey. Assume the friends are numbered \(1,2,3,4,5\), 6,7, and \(8 .\) Select four friends, using the two lines of numbers in the next column from a random number table. Read off each digit, skipping any digit not assigned to one of the friends. The sampling is without replacement, meaning that you cannot select the same person twice. Write down the numbers chosen. The first person is number 7 . $$ \begin{array}{lll} 07033 & 75250 & 34546 \\ \hline 75298 & 33893 & 64487 \end{array} $$ Which four friends are chosen?

Short Answer

Expert verified
The selected friends according to the random number table are the friends numbered \(7,3,2,5\).

Step by step solution

01

Reading the random numbers

Start from the top left corner of the array and read off each digit, skipping any digit that is not assigned to a friend (0, 9 and any number that occurs twice). The first number is 7, which is already indicated in the problem statement. The next valid number is 3, then 3 is skipped as this number is already selected, 2 is the next valid number, and the last valid number is 5.
02

Listing the selected friends

The friends selected were the ones corresponding to the numbers \(7, 3, 2, 5\) selected in step one. Make sure to not duplicate any number.

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Key Concepts

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

Statistics Education
Understanding statistics is crucial for making informed decisions based on data. The core idea behind statistics education is to equip students with the necessary tools to collect, analyze, interpret, and present data. Simple random sampling, the subject of our textbook exercise, is a fundamental technique used in statistics to ensure that every individual in a population has an equal chance of being selected for a sample.

When learning about simple random sampling, students should grasp that it's a method that prevents bias; it guarantees that the results are representative of the larger population. This technique is widely used in various fields such as market research, opinion polling, and health studies. By practicing with real-life examples, like selecting friends for a survey, students can see the practical applications of these statistical methods and understand their importance in research.
Random Number Table
A random number table is a tool used in statistics for carrying out simple random sampling. It consists of a grid of digits, each being independently chosen and equally likely to be any number between 0 and 9. These tables are designed to provide a sequence of numbers free of any patterns that could influence the results of a selection process.

To use a random number table effectively, students should follow a consistent method, like starting from a specific point in the table and moving in a predetermined direction (horizontally, vertically, or diagonally). When selecting a sample without replacement, the key is to skip over numbers not part of the population or those already chosen. If you need to choose among eight friends, for example, you'd ignore digits 9 and 0 and any repeats. Understanding this process enhances a student's ability to perform unbiased sampling and enhances their statistical reasoning skills.
Sampling Without Replacement
Sampling without replacement is a sampling method where each member of the population can only be chosen once for the sample. This is a crucial concept in both theory and practice because it ensures that the probabilities do not change as the sample is being drawn. In other words, once an individual is selected, they are not returned to the population for potential re-selection.

In our exercise, the sampling of friends for a survey is done without replacement, which is depicted by the rule of skipping any number that recurs. This results in a fair distribution and a more precise representation for statistical analysis. Students should note that sampling without replacement reduces the population size after each selection, thereby altering the probabilities for subsequent picks. It's imperative that this method is utilized correctly to avoid skewed data, which could invalidate the conclusions of a study or survey.

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Most popular questions from this chapter

Has trust in the legislative branch of government declined? A Gallup poll asked U.S. adults if they trusted the legislative branch of government in 2008 and again in 2017 . The results are shown in the table. $$ \begin{array}{|l|r|} \hline & \mathbf{2 0 0 8} & \mathbf{2 0 1 7} \\ \hline \text { Yes } & 399 & 358 \\ \hline \text { No } & 623 & 664 \\ \hline \text { Total } & 1022 & 1022 \\ \hline \end{array} $$ a. Find and compare the sample proportion for those who trusted the legislative branch in 2008 and in 2017 . b. Find the \(95 \%\) confidence interval for the difference in the population proportions. Assume the conditions for using the confidence interval are met. Based on the interval, has there been a change in the proportion of U.S. adults who trust the legislative branch? Explain.

In the 1960 presidential election, \(34,226,731\) people voted for Kennedy, \(34,108,157\) for Nixon, and 197,029 for third-party candidates (Source: www.uselectionatlas.org). a. What percentage of voters chose Kennedy? b. Would it be appropriate to find a confidence interval for the proportion of voters choosing Kennedy? Why or why not?

According to a 2017 Pew Research report, \(40 \%\) of millennials have a BA degree. Suppose we take a random sample of 500 millennials and find the proportion who have a BA degree. a. What value should we expect for our sample proportion? b. What is the standard error? c. Use your answers to parts a and \(\mathrm{b}\) to complete this sentence: We expect _____% to have a BA degree give or take _____%. d. Suppose we decreased the sample size from 500 to 100 . What effect would this have on the standard error? Recalculate the standard error to see if your prediction was correct.

According to a Gallup poll, \(45 \%\) of Americans actively seek out organic foods when shopping. Suppose a random sample of 500 Americans is selected and the proportion who actively seek out organic foods is recorded. a. What value should we expect for the sample proportion? b. What is the standard error? c. Use your answers to parts a and b to complete this sentence: We expect _____% of Americans to actively seek out organic foods when shopping, give or take _____%. d. Would it be surprising to find a sample proportion of \(55 \% ?\) Why or why not? e. What effect would decreasing the sample size from 500 to 100 have on the standard error?

Is simple random sampling usually done with or without replacement?

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