Eastwood's BA201 Assignments

Homework #18 Solutions (Chapter 12: exercises 2-10 even)

2.         a.         Multiple regression equation

            b.         One dependent, four independent

            c.         A regression coefficient

            d.         0.002

            e.         105.014, found by Y¢ = 11.6 + 0.4(6) + 0.286(280) + 0.112(97) + 0.002(35)

4.         a.         30.69 cubic feet

            b.         A decrease of 1.86 cubic feet, down to 28.83 cubic feet.

            c.         Yes, logically, as the amount of insulation increases and outdoor temperature increases, the consumption of natural gas decreases.

6.         a.         26

            b.         5

            c.         0.3 found by 60/200

            d.         2.65 found by

8.         a.         Source       DF       SS     MS       F

                       Regression    5      1500   300.     9.00

                       Error        15       500    33.33

                       Total        20      2000

            b.         H_o:  b₁ = b₂ = b₃ = b₄ = b₅ = 0               H₁:  Not all b‘s are 0    

                        Reject H_o if F > 2.90

                        Reject H_o.  Not all of the regression coefficients are zero.

            c.         For X₁               for X₂               for X₃               for X₄               for X₅

                        H_o:  b₁ = 0        H_o:  b₂ = 0        H_o:  b₃ = 0        H_o:  b₄ = 0        H_o:  b₅ = 0

                        H₁: b₁ ¹ 0         H₁: b₂ ¹ 0         H₁: b₃ ¹ 0         H₁: b₄ ¹ 0         H₁: b₅ ¹ 0

                        t = 4.00             t = -0.833         t = 1.00             t = -3.00           t = 4.00

                        Reject H_o if t > 2.131 or t < -2.131

                        Delete variable 2 and 3 , keep 1, 4 and 5

10.        H_o:  b₁ = 0        H₁: b₂ = 0

            H_o:  b₁ ¹ 0        H₁: b₂ ¹ 0

            H_o is rejected if t < -2.074 or t > 2.074

            The second variable can be deleted.

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