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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

According to a 2017 article in The Washington Post, \(72 \%\) of high school seniors have a driver's license. Suppose we take a random sample of 100 high school seniors and find the proportion who have a driver's license. Find the probability that more than \(75 \%\) of the sample has a driver's license. Begin by verifying that the conditions for the Central Limit Theorem for Sample Proportions have been met.

Suppose that, when taking a random sample of three students' GPAs, you get a sample mean of \(3.90 .\) This sample mean is far higher than the collegewide (population) mean. Does that prove that your sample is biased? Explain. What else could have caused this high mean?

Of 1019 U.S. adults responding to a 2017 Harris poll, \(47 \%\) said they always or often read nutrition labels when grocery shopping. a. Construct a \(95 \%\) confidence interval for the population proportion of U.S. adults who always or often read nutrition labels when grocery shopping. b. What is the width of the \(95 \%\) confidence interval? c. Name a confidence level that would produce an interval wider than the 95\% confidence interval. Explain why you think this interval would be wider than a \(95 \%\) confidence interval. d. Construct the interval using the confidence level you proposed in part c and find the width of the interval. Is this interval wider than the \(95 \%\) confidence interval?

According to The Washington Post, \(72 \%\) of high school seniors have a driver's license. Suppose we take a random sample of 100 high school seniors and find the proportion who have a driver's license. 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 their driver’s license, give or take _____%. d. Suppose we increased the sample size from 100 to 500 . What effect would this have on the standard error? Recalculate the standard error to see if your prediction was correct.

According to a 2017 Pew Research Center report on voting issues, \(59 \%\) of Americans feel that the everything should be done to make it easy for every citizen to vote. Suppose a random sample of 200 Americans is selected. We are interested in finding the probability that the proportion of the sample who feel with way is greater than \(55 \%\). a. Without doing any calculations, determine whether this probability will be greater than \(50 \%\) or less than \(50 \%\). Explain your reasoning. b. Calculate the probability that the sample proportion is \(55 \%\) or more.

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