a random sample of 42 college graduates revealed that they worked an average of 7.3 years on the job before being promoted. the sample standard deviation was 2.9 years. using the 0.99 degree of confidence, what is the confidence interval for the population mean?

Respuesta :

The confidence interval for the population mean with 99% confidence interval is (6.90;8.50).

What is meant by confidence interval?

A confidence interval is a set of values that, with a particular level of certainty, includes a population value. When a population mean is between an upper and lower interval, it is frequently stated as a percentage.

The population mean is mean [tex]\bar{x}[/tex]=7.3.

The sample's standard deviation is 2. 9

Number of samples: 42

The range of possibilities for the mean, [tex]\bar{x}[/tex]

The confidence interval for the mean is

[tex]\bar{x}[/tex] ± (σ/√n)

To calculate the critical value, we must first determine the degrees of freedom, which are given by:

df=n-1

df=42-1

df=41.

Since the confidence level is 0.99 or 99%, the values of and can be used to calculate the critical value using Excel, a calculator, or a table is 2.701

7.3-2.701(2.9/√42)=6.9013

7.3+2.701(2.9/√42)=8.5086

The 99% confidence interval in this instance would therefore be provided by (6.90;8.50).

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