Chapter 4 - Section 4.2 - Assess Your Understanding - Vocabulary and Skill Building - Page 215: 11f

$Σresidual^2=51.441$ (Other answers are possible depending on the initial points chosen.)

Since $ŷ =−0.833x+120$ $Σresidual^2=Σ(y_i-ŷ _i)^2=Σ[y_i-(−0.833x_i+120)]^2=Σ(y_i+0.833x_i-120)^2$ $Σresidual^2=(100+0.833\times20-120)^2+(95+0.833\times30-120)^2+(91+0.833\times40-120)^2+(83+0.833\times50-120)^2+(70+0.833\times60-120)^2$ $Σresidual^2=51.441$