/*! 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 32 32\. Parking II Suppose that, fo... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

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?

Short Answer

Expert verified
Increasing the confidence level to \(95 \%\) results in a wider confidence interval which offers more assurance that the true mean falls within this range, but it also decreases precision. This lack of precision might hinder the planning process. One way to maintain a high confidence level while achieving more precise estimates is by increasing the sample size.

Step by step solution

01

Understand what changing the confidence interval does

Increasing the confidence level from \(90 \%\) to \(95 \%\) makes the confidence interval wider. This means that the estimate of the mean daily income from parking fees is less precise, but we can be more confident that the true value lies within the interval.
02

Analyze the benefits of a \(95 \%\) confidence interval

By using a \(95 \%\) confidence interval instead of a \(90 \%\) interval, the city increases the likelihood that the true mean of the daily earnings falls within this interval. This higher level of confidence can be beneficial if the city wants to minimize the risk of underestimating their income, since a wider interval will provide a more conservative estimate.
03

Analyze the drawbacks of a \(95 \%\) confidence interval

While a \(95 \%\) confidence interval provides a higher level of confidence, it also yields a wider interval, which could be disadvantageous for the planners. A wider interval means less precise estimation, which might lead to less accurate budget planning. If the interval is too wide, it may be challenging for them to make detailed plans and predictions.
04

Suggest a way to achieve a better interval estimate

They could achieve a better interval estimate by increasing their sample size. A larger sample size provides more data, which would naturally decrease the width of the confidence interval, and increase the precision of the mean estimate, all while maintaining the desired confidence level. Another solution could be adjusting their desired level of confidence based on the precision they need for their planning purposes.

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.

Sample Size
Understanding sample size is fundamental when it comes to creating statistically reliable estimates. In the context of estimating the mean daily income from parking fees, the sample size refers to the number of days or the number of parking transactions that the city analyzes. A larger sample size tends to yield more precise estimates because it is more representative of the population.

A key point to remember is that increasing the sample size decreases the margin of error in the confidence interval. This means the planners could get a closer estimate of the true daily income. However, there must be a balance since collecting data from more days or transactions requires more resources. The city should consider both the costs and benefits of increasing the sample size, ensuring that it's sufficiently large to support accurate budget planning.
Statistics
Statistics is the science that helps us understand data. In the city's case, statistics come into play when they use a sample to make inferences about the population's mean daily income from parking fees. This practice involves the use of a confidence interval, which gives a range where the actual mean is likely to be located.

The confidence level (90%, 95%, etc.) indicates how certain we are that this interval contains the true mean. A 95% confidence level is standard in statistics because it balances a reasonable level of certainty without requiring too wide of an interval. Nevertheless, statisticians must use their expertise to decide the appropriate confidence level based on the context and needs of the problem at hand.
Mean Daily Income Estimation
When estimating the mean daily income from parking fees for budget planning, the mean is the average income that's earned each day. It's an essential figure for constructing a financial forecast and allocating resources effectively. The estimation of this mean is typically done through a confidence interval.

To generate a robust estimation, the sample data needs to be collected in a way that avoids bias and captures different trends and patterns, such as varying on weekdays vs. weekends. It's also important to factor in any anomalies or outliers that could skew the mean. The city could use the improved estimation of mean daily income not only for budgeting but also for making strategic decisions about pricing, the addition of new parking spaces, or adjusting time limits.
Budget Planning
Budget planning is a forward-looking activity crucial for the city's fiscal stability. It requires accurate predictions about future income and expenses. An accurate estimate of the mean daily income from parking fees helps the city anticipate revenues and plan for infrastructure improvements, public services, and other investments.

An overestimation of parking income could lead to overspending, while underestimation might mean missed opportunities due to unavailable funds. Therefore, it's essential that the city uses a confidence interval that provides a reliable estimate while taking into account the level of precision necessary for effective budget planning. By aligning the confidence interval's level of precision with the planning horizon and strategic goals, the city can make informed decisions that benefit the community.

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

Golf balls The United States Golf Association (USGA) sets performance standards for golf balls. For example, the mean initial velocity of the ball may not exceed 250 feet per second when measured by an apparatus approved by the USGA. Suppose a manufacturer introduces a new kind of ball and provides a sample for testing. Based on these data, the USGA comes up with a \(95 \%\) confidence interval for the mean initial velocity from 240.8 to 259.9 feet. What does this say about the performance of the new ball?

Meal plan After surveying students at Dartmouth College, a campus organization calculated that a \(95 \%\) confidence interval for the mean cost of food for one term (of three in the Dartmouth trimester calendar) is (\$1372, \$1562). Now the organization is trying to write its report and is considering the following interpretations. Comment on each. a. \(95 \%\) of all students pay between \(\$ 1372\) and \(\$ 1562\) for food. b. \(95 \%\) of the sampled students paid between \(\$ 1372\) and \(\$ 1562\) c. We're \(95 \%\) sure that students in this sample averaged between \(\$ 1372\) and \(\$ 1562\) for food. d. \(95 \%\) of all samples of students will have average food costs between \(\$ 1372\) and \(\$ 1562\). e. We're \(95 \%\) sure that the average amount all students pay is between \(\$ 1372\) and \(\$ 1562\).

At work Some business analysts estimate that the length of time people work at a job has a mean of 6.2 years and a standard deviation of 4.5 years. a. Explain why you suspect this distribution may be skewed to the right. b. Explain why you could estimate the probability that 100 people selected at random had worked for their employers an average of 10 years or more, but you could not estimate the probability that an individual had done so.

The sampling distribution of a mean tends toward one like this-a Normal model centered at \(\mu\) with standard deviation \(\sigma / \sqrt{n}\). We know that our sample mean \(\bar{y}\) is somewhere in this picture. But where? \(95 \%\) of samples will have means within 1.96 standard deviations of \(\mu .\) So, if we made \(\mu\) traps for each sample going out \(1.96 \times \frac{\sigma}{\sqrt{n}}\) on either side of \(\bar{y}, 95 \%\) of those traps would capture \(\mu .\)

Popcorn Yvon Hopps ran an experiment to determine optimum power and time settings for microwave popcorn. His goal was to find a combination of power and time that would deliver high-quality popcorn with less than \(10 \%\) of the kernels left unpopped, on average. After experimenting with several bags, he determined that power 9 at 4 minutes was the best combination. To be sure that the method was successful, he popped 8 more bags of popcorn (selected at random) at this setting. All were of high quality, with the following percentages of uncooked popcorn: \(7,13.2,10,6,7.8,2.8,2.2,5.2 .\) Does the \(95 \%\) confidence interval suggest that he met his goal of an average of no more than \(10 \%\) uncooked kernels? Explain.

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.