Purchase Solution

Building confidence interval under either t or z distribution

Not what you're looking for?

Ask Custom Question

Q4
A system consists of five identical components connected in series as shown:

As soon as one component fails, the entire system will fail. Suppose each component has a lifetime that is exponentially distributed with mean λ = 2 years and that component fail independently of one another.
I. What is the probability that the first component is still working after 1 year?
II. What is the probability that the entire system fails in 1 year?

Q5
The monthly starting salaries of students who receive an MBA degree have a standard deviation of $70. What sample size should be selected so that there is a 95% confidence of estimating the mean monthly within a sampling error of $ 18 or less?

Q6
The compressive strength of a concrete is being used by an engineer and the results were recorded as follows:
221, 222, 231, 223, 230, 215, 210
Construct a 95% confidence interval on the mean strength.

Attachments
Purchase this Solution
Solution Summary

The solution gives detailed steps on finding the probability and building confidence interval under either t or z distribution.

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.

Measures of Central Tendency

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

Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

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

  • Confidence Interval

    Then if you can use either a t- or z- distribution, give the associated critical value (critical t- or z- score) from that distribution to reach the given confidence level. Please see the attached file. The solution answers the question below.

  • Significance Testing Format

    Then the 95% confidence interval is (102.11, 183.19) Note: the 95% confidence interval using t value (under small sample assumption) is wider than the confidence interval using z value (under large sample assumption).

  • Student's t and Standard Normal Comparison

    example, show that for a given confidence level; the Student's t confidence interval for the mean is wider than if we use a z-value.

  • Confidence interval and t-distributions

    Use a normal distribution or a t-distribution to construct a 90% confidence interval or the mean. Which distribution should be used to construct the 90% confidence interval? A.

  • Estimates and Sample Sizes - Stats

    (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?

  • Normal Probability, Confidence interval & Hypothesis Testing

    T distribution is more similar to normal for n =20 that d.f =10 XXV Which two T VALUES bracket 2.50 on the df = 15 distribution?

  • Distribution; Standard Deviation; Mean; Confidence Interval

    b) Estimate with 95% confidence the mean weight of the container. Make sure you give the conditions under which this confidence interval is valid.

  • Confidence Intervals, Differences Between T And Z Distribution

    319995 Confidence Intervals, Differences Between T And Z Distribution 1. What do confidence intervals represent? What is the most controllable method of increasing the precision (narrowing) of the confidence interval?

  • confidence interval, distribution and probability

    In these problems, since the sample sizes are all large (greater than 30), we use the Z distribution rather than a t distribution for finding confidence intervals.

View More Related Solutions