Purchase Solution

Confidence interval, error of estimate, sample size

Not what you're looking for?

Ask Custom Question

In the publication Employment and Earnings, information on the ages of people in the civilian labor force was published. Seventy-five people in the civilian labor force are randomly selected. The mean age is 37.4 years with a standard deviation of 10.3 years.

a. Find the 99% confidence interval for the mean age.
b. What is the error of estimate for the 90% confidence interval?
c. What is the minimum sample size that is needed for the 95% confidence interval, if the maximum error of estimate is 2.1 years?

Purchase this Solution

Solution Summary

The solution calculates confidence interval of the mean age, error of estimate for for the confidence interval and sample size for the confidence interval.

Solution Preview

a. Find the 99% confidence interval for the mean age.

Mean=M =37.4years

Standard deviation =s=10.3years

sample size=n=75

sx=standard error of mean=s/square root of n=1.1893= ( 10.3 /square root of 75)

Confidence level=99%

a (alpha) =1%=100% -99%

or Significance level=a (alpha) =0.01(expressed as a number )

No of tails=2

Since sample size=75>=30use normal distribution

Z at the ...

Purchase this Solution


Free BrainMass Quizzes
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.

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.