Statistics Quiz 5

Quiz 5 Page 366 Question #6

At the .05 significance level, can we conclude that there is more variation in the oil stocks? Sample Population A = Sample mean A = Sample standard deviation A = Sample standard deviation A squared = Sample df A = 10-1=9 Sample Population B = Sample mean B = Sample standard deviation B = Sample df B = 8-1=7 Sample standard deviation B squared = Step 1. H0 SA2 < SB2 H1 SA2 ≥ SB2 Step 2. Step 3. Step 4. .05 significance level given Reject H0 if F is > 3.68 (got by looking the df numerator and df denominator in table) F = 15.21 12.25 Step 5. 1.2416 10 12.6 3.9 15.21 8 10.9 3.5 12.25 df numerator = df denominator = 9 7

H0 is rejected. We conclude that there is more variation in oil stocks.

Page 376 Question #10

At the .05 significance level, can she conclude there is a difference in the mean number of hours spent per week by industry?

Banking 12 10 10 12 10 54 10.8 Step 1.

Retail 8 8 6 8 10 40 8 H0: µN = µP H1: µN = µP

Insurance 10 8 6 8 10 42 136 8.4 0 Step 2. Step 3. Step 4. .05 significance level given Reject H0 if t is > 1.812 ((got by looking up in the t table significance level of .05 with a degree of flexibility of 10 (sample 12 - 2 = 10)) t = .307√12-2 √1-(.307)2 0.9708 0.9517 1.020

Step 5.

H0 is not rejected. There is not a positive association between the size of the home and the selling price.

Page 445 Question #4

Monthly Natural Gas Thickness of Outdoor Consumption Insulation (inches), Temperature (cubic feet), Y X1 (F), X2 30.3 6 40 26.9 12 40 22.1 8 49

On the basis of the sample results, the regression equation is: Ŷ = 62.65 - 1.86X1 - .52X2 a. How much natural gas can homeowners expect to use per month if they install 6 inches of insulation and the outdoor temperature is 40 degrees F? Ŷ = 62.65 - 1.86(6) - .52(40) b. 30.69

What effect would installing 7 inches of insulation instead of 6 have on the monthly natural gas consumption (assuming the outdoor temperature remains at 40 degrees F)? Ŷ...