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# Confidence levels, Regression analysis, and ANOVA

See attached file.

2. A random sample of 10 examination papers in a course, which was given on a pass or fail basis, showed the following scores.

Create a 95% confidence interval for the population with a mean of 75 and Standard Deviation of the population of 10.

A. Does this mean fall within that interval, what does that mean?
B. Using the critical value approach, do a hypothesis test to see if these scores are realistic compared to the population

3. A regression analysis between a dependent variable (Y) and an independent variable (X) was performed and part of the Excel results is shown below.

Answer the following questions based on the above information and use a 95% confidence.

a. Is the regression model significant at 95% confidence? Why or why not. Fully explain.
b. Is X significant? Why or why not. Fully explain.
c. Compute the value of R-square.
d. Determine the multiple R.
e. Compute the standard error.
f. What has been the sample size for this problem?

4. A computer manufacturer has developed a regression model relating Sales (Y in \$10,000) with four independent variables. The four independent variables are Price (in dollars), Competitor's Price (in dollars), Advertising (in \$1000) and Type of computer produced (Type = 0 if desktop, Type = 1 if laptop). Part of the regression results are shown below.

a. What has been the sample size?
b. Determine the coefficient of determination.
c. Compute the test statistic t for each of the four independent variables.
d. Determine the p-values for the four variables.
e. At 95% confidence, which variables are significant? Explain how you arrived at your conclusion.
f. At 95% confidence, test to see if the regression model is significant.

Use Excel for these 3 practice problems.

#### Solution Summary

Complete, Neat and Step-by-step Solutions are provided in the attached file.

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