Roberta Refuse, the head sanitation engineer for the metropolis of Cramer, would like to assess the impact of a statewide recycling law on trash collection in Cramer. The law prohibits the disposal of yard waste in trash cans. If this law is having an impact, the amount of trash collected will drop. Weekly trash collection data are available. The dependent variable is total tons of trash collected. The in dependent variables are X₁, the number of inches of rainfall the previous week (grass grows more when it rains); X₂, the mean Fahrenheit temperature for the previous week (grass grows better when it is warm); and X₃, a short-term impact variable coded 0 before the recycling law went into effect and coded 1 afterward. Roberta gets the following results:

Interpret the slopes, intercept, and coefficient of determination. Test the slopes for significance, and explain what this equation says about the recycling law.

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Sb₁ = 31 Ŷ = 12,405 + 140X₁ + 7.4X₂ - 575X3 Sb₂ = 2.0 Sb3 = 45 Sy = 327 R² = .63 N = 75