Z-test

Can the sample standard deviations s1 and s2 be used in place of the population standard deviations σ1 and σ2?

1. "Testing the Difference between Two Means." (Note: Please respond to only one (1) of the following two (2) bulleted items)

What two assumptions must be met when you are using the z test to test differences between two means? 

2. Use the Internet to research an annual report of a retail company.

Then, imagine you are an investor or creditor; suggest the ratios that you believe would provide an investor or creditor with the most important information needed to make accurate predictions about the company’s financial condition. When analyzing a company, is it more important to compare the ratios to competitors or to the company’s previous history?

Can the sample standard deviations s1 and s2 be used in place of the population standard deviations σ1 and σ2?

What two assumptions must be met when you are using the z test to test differences between two means?

1. "Testing the Difference between Two Means." (Note: Please respond to only one (1) of the following two (2) bulleted items)