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Teachers Software analysis of the salaries of a random sample of 288 Nevada teachers produced the confidence interval shown below. Which conclusion is correct? What's wrong with the others? with \(90.00 \%\) Confidence, \(t\) -interval for \(\mu: 43454<\mu(\) TchPay \()<45398\) a. If we took many random samples of 288 Nevada teachers, about 9 out of 10 of them would produce this confidence interval. b. If we took many random samples of Nevada teachers, about 9 out of 10 of them would produce a confidence interval that contained the mean salary of all Nevada teachers. c. About 9 out of 10 Nevada teachers earn between \(\$ 43,454\) and \(\$ 45,398 .\) d. About 9 out of 10 of the teachers surveyed earn between \(\$ 43,454\) and \(\$ 45,398\). e. We are \(90 \%\) confident that the average teacher salary in the United States is between \(\$ 43,454\) and \(\$ 45,398\).

Short Answer

Expert verified
The correct conclusion is option b: 'If we took many random samples of Nevada teachers, about 9 out of 10 of them would produce a confidence interval that contained the mean salary of all Nevada teachers.' The confidence interval given doesn't indicate the salary range of individual teachers, rather it represents the mean salary range for all teachers, based on a sample of 288. Other conclusions either misinterpret the confidence interval or extrapolate beyond the data.

Step by step solution

01

Analyzing the Correct Interpretation

The interpretation of confidence interval needs proper understanding. 'With 90% confidence, t-interval for \(\mu\): 43454<\(\mu\)(TchPay)<45398' means that based on the random sample of 288 Nevada teachers, we are 90% confident that the true mean salary of all Nevada teachers lies within this interval ($43,454 and $45,398). This interpretation aligns with option b in the multiple choice.
02

Addressing Incorrect Conclusions

Other answer choices incorrectly interpret or extrapolate statistics. Options a and c misunderstand the concept by assuming that the confidence interval is for individual salaries in the same sample or different samples of the same size. Option d is incorrect because the interval isn't about individual salaries in the survey but rather the mean salary. Finally, option e is wrong as the stated interval is specifically for Nevada teachers, not teachers across the United States.

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Key Concepts

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

Nevada Teachers
Nevada's teachers represent a diverse group of educators working in various fields across the state's school districts. In statistical studies, such as the one in this exercise, it's vital to consider the context of the population you are studying.
This study focused solely on Nevada teachers which means conclusions drawn from the data apply specifically to this group only.
  • The sample includes teachers from different schools and districts within Nevada.
  • Each teacher's salary adds valuable data to understanding the overall salary trends.
  • The insights from this sample can help shape salary-related discussions statewide.
By focusing on Nevada teachers, the study aims to provide meaningful insights into the particular economic landscape for educators in this state.
Mean Salary
The mean salary is a crucial concept in this statistics problem. It represents the average salary of all Nevada teachers in the study. Understanding the mean helps policymakers and education leaders make informed decisions.
In the confidence interval provided, the mean salary is what the interval estimates.
  • The mean is calculated by summing all teachers' salaries and dividing by the number of teachers sampled.
  • It's central to assessing the pay scale and how it compares to other regions or states.
  • Variances in the mean salary could suggest areas for further investigation or reform.
In this exercise, the mean gives insight into the possible range of typical teacher salaries within the specific sample.
Random Sampling
Random sampling is a statistical method used to select a subset of individuals from a larger population. It aims to provide an unbiased representation of the entire group. In this exercise, random sampling was used to pick 288 Nevada teachers.
This helps ensure that the observed confidence interval accurately reflects the wider population.
  • Random sampling reduces selection bias, increasing result accuracy.
  • It allows generalization of findings from the sample to the entire population of Nevada teachers.
  • This method is essential for achieving a reliable confidence interval.
Understanding random sampling is key for interpreting the study's results and lending credibility to the analysis.
Interpretation of Statistics
Interpreting statistics correctly is crucial for drawing valid conclusions. A confidence interval, like the one in the exercise, encapsulates this concept. It's important not to confuse the confidence interval's meaning with individual teacher salaries or applicability beyond the study's context.
  • The interval estimates the mean salary for all Nevada teachers, not specific individual salaries.
  • A 90% confidence level indicates the interval will contain the true mean salary in 90 out of 100 similar studies.
  • Misinterpretation could lead to incorrect assumptions or policy decisions.
Grasping the correct interpretation allows stakeholders to make data-driven decisions and understand the significance and limitations of the analysis.

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Most popular questions from this chapter

Home sales The housing market recovered slowly from the economic crisis of 2008 . Recently, in one large community, realtors randomly sampled 36 bids from potential buyers to estimate the average loss in home value. The sample showed the average loss from the peak in 2008 was \(\$ 9560\) with a standard deviation of \(\$ 1500\). a. What assumptions and conditions must be checked before finding a confidence interval? How would you check them? b. Find a \(95 \%\) confidence interval for the mean loss in value per home.

32\. Parking II Suppose that, for budget planning purposes, the city in Exercise 30 ?needs a better estimate of the mean daily income from parking fees. a. Someone suggests that the city use its data to create a \(95 \%\) confidence interval instead of the \(90 \%\) interval first created. How would this interval be better for the city? (You need not actually create the new interval.) b. How would the \(95 \%\) interval be worse for the planners? c. How could they achieve an interval estimate that would better serve their planning needs?

Snow Based on meteorological data for the past century, a local TV weather forecaster estimates that the region's average winter snowfall is \(23 "\), with a margin of error of ±2 inches. Assuming he used a \(95 \%\) confidence interval, how should viewers interpret this news? Comment on each of these statements: a. During 95 of the past 100 winters, the region got between \(21 "\) and \(25 "\) of snow. b. There's a \(95 \%\) chance the region will get between \(21 "\) and \(25 "\) of snow this winter. c. There will be between \(21 "\) and \(25 "\) of snow on the ground for \(95 \%\) of the winter days. d. Residents can be \(95 \%\) sure that the area's average snowfall is between \(21 "\) and 25 ". e. Residents can be \(95 \%\) confident that the average snowfall during the past century was between \(21 "\) and \(25 "\) per winter.

Shoe sizes revisited Chapter 2 ?, Exercise 16 showed the histogram of the European shoe sizes from a sample of 269 college students. Looking at the men only, a \(95 \%\) confidence interval for the mean shoe size shows: The student knows that European shoes are sized only in whole and half sizes, so is surprised that most men wear size 44.5 shoes. What is wrong with the student's reasoning?

Salmon A specialty food company sells whole King Salmon to various customers. The mean weight of these salmon is 35 pounds with a standard deviation of 2 pounds. The company ships them to restaurants in boxes of 4 salmon, to grocery stores in cartons of 16 salmon, and to discount outlet stores in pallets of 100 salmon. To forecast costs, the shipping department needs to estimate the standard deviation of the mean weight of the salmon in each type of shipment. a. Find the standard deviations of the mean weight of the salmon in each type of shipment. b. The distribution of the salmon weights turns out to be skewed to the high end. Would the distribution of shipping weights be better characterized by a Normal model for the boxes or pallets? Explain.

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