HW will be asked. Please come to the class early so that you do not miss the quiz!

1. Run a regression between price and area (sqft) for data in “housing ” worksheet.

a. Estimate the population simple linear regression line that shows a relationship between the area and price of a house. (Price depends on the size of the house)

b. Interpret the intercept and the slope of the line.

c. Estimate the standard deviation of the error, s.

d. Evaluate the model by testing the slope coefficient to see if there is a relationship at the 5% significance level. Construct the test hypothesis and use the regression output for this test.

2. (Problem 10.24, 10.48, 10.68, 10.79). Spreading Rate of spilling liquid. A DuPont Corp. Engineer calculated the mass (in pounds) of a 50-gallon methanol spill after a period of time ranging from 0 to 60 minutes. Use data in ‘Liquidspill’ sheet.

a. Do the data indicate that the mass of the spill tends to diminish as time increases? If so, how much will the mass diminish each minute?

b. Is there sufficient evidence for a linear relationship? Test using α=0.05.

c. Give an interval estimate (95%) of the decrease in spill mass for each minute of elapsed time.

d. Find and interpret r and r2.

e. Find a 99% confidence interval for the mean mass of all spills with an elapsed time of 15 minutes. Interpret the result.

f.

Find a 99% confidence interval for the mass of a single spill with an elapsed time of 15 minutes.

Interpret the result.

g. Compare the intervals in part e and f. Explain why they are different. Which interval is wider?

Will this always be the case?

3. Refer to Florida Trend Maganize’s (April 2002) data on law firms with headquarters in the state of

Florida. (Data saved in the FLALAW sheet). Suppose you want to predict the number of law offices (y) based on the number of lawyers (x) at the firm.

a. Use the method