The authors of the paper “Power-Load Prediction Based on Multiple Linear Regression Model” (Boletin Tecnico [2017]: 390–397) were interested in predicting the load on the electric power system in China using data on y = Power consumption (in hundreds of millions of kwh), x₁ = Population (in millions), and x₂ = Gross domestic product (in billions of dollars), for 21 years. The model equation proposed in the paper is

y = -113,527 + 0.974x₁ + 0.057x₂ + e

a. According to this model, what is the mean power consumption for a year if the population was 130,000 million and the gross domestic product was 400,000 billion dollars?

b. Interpret the value of β₁ in this model.