Question

Starting salaries of 90 college graduates who have taken a statistics course have a mean of $43,993 and a standard deviation of $9,144. Using 99% confidence level, find the following:

A. Margin of error E

B. The confidenxe interval for the mean u

Answer 1

A. Margin of error is given by:

B.

We need to construct the 99% confidence interval for the population mean μ. The following information is provided:

Sample Mean =	43993
Sample Standard Deviation (s) =	9144
Sample Size (n) =	90

The critical value for α=0.01 and df=n−1=89 degrees of freedom is . The corresponding confidence interval is computed as shown below:

​

Therefore, based on the data provided, the 99% confidence interval for the population mean is 41455.918<μ<46530.082, which indicates that we are 99% confident that the true population mean μ is contained by the interval (41455.918,46530.082).

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