Purchase Solution

Estimates and Sample Sizes - Stats

Not what you're looking for?

Ask Custom Question

You can use StatCrunch or the appropriate equations for calculating the confidence intervals.

I. A personnel manager at a large firm needs to estimate the mean length of stay, ? of its employees. She takes a random sample of employees and finds the sample mean (?x) to be 25 years.

a) Use the above data, ?x = 25, to find a 90% confidence interval for ? if the employee sample size is 64, and a known population standard deviation ? = 16.

What is the appropriate distribution (z or t)? ___________

b) What is its numerical value (obtain answer from the appropriate table, z or t?
___________

c) What is the Confidence Interval? (Provide answer to at least two decimal places)

________________________ ________________________

II. Find a 95% Confidence Interval for the mean length of stay (?) of the employees of the large company if the point estimate for µ is?x =25, the sample size is 9 and the sample standard deviation s = 12. (You can assume the distribution is normal).

a) What is the appropriate distribution (z or t)? ___________

b) What is its numerical value (obtain answer from the appropriate table, z or t?
___________

c) What is the Confidence Interval? (Provide answer to at least two decimal places.)

________________________ ________________________.

Purchase this Solution
Solution Summary

The solution provides step-by-step answers that estimates and provides sample sizes in the given statistics questions given.

Solution Preview

Please refer to the attachment for the full solution.

Problem-I: A personnel manager at a large firm needs to estimate the mean length of stay of its employees. She takes a random sample of employees and finds the sample mean (x) to be 25 years. Use the above data, x = 25, to find a 90% confidence interval for µ. If the employee sample size is 64, and a known population standard deviation σ = ...

Solution provided by:
Anwesha Ghosh, MSc
Education
  • MSc, Osmania University
  • MSc, Indian Institute of Technology - Roorkee (I.I.T.-ROORKEE)
  • BSc, Banaras Hindu University
Recent Feedback
  • "Very fast turnaround. Excellent communication! Much appreciated!"
  • "excellent"
  • "excellent"
  • "excellent work"
  • "Fantastic..great solution and very well explained!!!!"
Purchase this Solution
Free BrainMass Quizzes
Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

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.

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.

Measures of Central Tendency

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

View More Free Quizzes
Related BrainMass Solutions

  • P Value and Pooled Variance Case

    Since the sample sizes n1=330 and n2=310 are very large, we can approximate it to use z-test.

  • Random Samples from Two Binomials

    b) Repeat part a increasing the sample sizes to 400. c) Describe what happens to the p-value when the sample sizes increase. Assuming alpha = 0.05 ...

  • Estimates and sample sizes

    This solution discusses estimates and sample sizes.

  • Determining Television Audience Sizes

    What sample sizes are necessary at population sizes of 1 billion, 10,000, and 100 with a confidence interval of 5 and a 95 percent confidence level? Explain the effect population size has on sample size.

  • background for ANOVAs and t-tests

    Non-parametric stats should be used with small sample sizes or when nothing is known about the population (no known parameters).

  • Statistics

    b) Repeat part a changing the sample sizes to n1 = 15 and n2 = 15. c) Describe what happens to the test statistic when the sample sizes decrease. (a) p- value = 0.06688 > 0.05. Therefore we fail to reject H0.

  • Statistics ANOVA: lumen output of 3 brands of light bulbs

    (c) How would the conclusion of (b) be affected if the sample sizes were 4 instead of 8? Answer without doing calculations, and explain. In this case the F statistic have d.f (2,9).

  • Population Means and Confidence Intervals

    Determine the mean of the sample, which was used to determine the interval estimate. 1. 16 2. 47.5 Please see the attached file for a step-by-step explanation. This solution calculates sample sizes used to determine interval estimates.

  • How to choose an appropiate sample size

    The managers plan to cheese a random sample of completion times and estimate u via the sample.

View More Related Solutions