A Regression Model Relating a Dependent Variable, Y, with One $\alpha$

Essay

A regression model relating a dependent variable, y, with one independent variable, x₁, resulted in an SSE of 400. Another regression model with the same dependent variable, y, and two independent variables, x₁ and x₂, resulted in an SSE of 320. At $\alpha$ = .05, determine if x₂ contributed significantly to the model. The sample size for both models was 20.