Answer
a) $G(30)=81$
b) Underestimated by $2$ percents
Work Step by Step
Use the formula of $$G(x)=-0.01x^2+x+60$$
a) Calculate: $$G(30)=-0.01(30^2)+30+60=81$$
b) Because $81<83$, it means that $G(30)$ underestimates the data shown in the bar graph by $83-81=2$ percents.
