Purchase Solution

Confidence Intervals, Sample Size

Not what you're looking for?

Ask Custom Question

In order to determine the fuel efficiency for the Subaru Impreza the following information was gathered:

a) A random sample of 12 Imprezas were driven yielding the following miles per gallon (mpg).

25.1 24.6 22.5 27.8 26.1 21.0 23.9 28.4 24.4 23.5 26.2 20.7

Create a 95% confidence interval estimate for the population mean mpg's for the Subaru Impreza.
b) Later, a larger sample of 100 Imprezas were driven yielding an average of 24.6 mpg's and a standard deviation of 2.8 mpg's. Create a 98% confidence interval estimate for the population mean mpg's for the Subaru Impreza.

c) What is the minimum sample size that would be required to estimate this population's mean to within + or - .05 mpgs with a 90% confidence? (Assume standard deviation = s from part b)

Purchase this Solution
Solution Summary

The expert calculates Confidence Intervals and Sample Size.

Purchase this Solution
Free BrainMass Quizzes
Measures of Central Tendency

This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.

Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

Measures of Central Tendency

Tests knowledge of the three main measures of central tendency, including some simple calculation questions.

Know Your Statistical Concepts

Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.

View More Free Quizzes
Related BrainMass Solutions

  • Estimations, Confidence intervals, Sample Size

    321395 Estimations, Confidence intervals, Sample Size Why are estimations and confidence intervals important? Do confidence intervals and estimation play a role in the selection of sample size? Please explain your answer.

  • Finding Sample Amount for Population Mean

    The sample mean b. The 80% confidence intervals for the population mean= c. The 50% confidence intervals for the population mean= d. The 98% confidence intervals for the population mean= e.

  • Statistics Questions

    How do your confidence intervals change as n increases? 7. Return to a sample size of 100. Compare your confidence intervals for confidence levels of 90%, 95%, and 99%.

  • Confidence Intervals, Differences Between T And Z Distribution

    Confidence intervals represent ESTIMATION, about "the true mean of a population based on a random sample."

  • Confidence intervals and hypothesis tests

    This solution answers and explains three multiple choice questions about confidence intervals, sample size, and hypothesis tests.

  • Computing Confidence Intervals Concept

    It should be noted that larger the sample size, the lower is the standard error and narrower is the confidence interval. Therefore, a larger sample size would give a better estimate of the population mean.

  • Confidence Intervalss

    137383 Confidence Intervals Calculate and interpret 90%, 95%, and 99% confidence intervals for both groups of approaches. Also provide 90%, 95%, and 99% confidence intervals for both groups when the sample size is increased from 10 to 50.

  • Solve: 99% Confidence Interval

    What is the effect of increasing the sample size on the width of the confidence intervals? Round to two decimal places. What is the effect of the sample size on the width of the confidence interval?

  • Evalutating Confidence Intervals

    confidence intervals for statistical abstracts of the United States.

  • Values for confidence intervals

    The solution finds the z and t values for the follow confidence intervals. Note that sample size does not apply for a z value.

View More Related Solutions