[tex]\bf \cfrac{\stackrel{model}{length}}{\stackrel{actual}{length}}\qquad 1:83\qquad \cfrac{1}{83}\implies \cfrac{1}{83}=\cfrac{10.5}{x}\implies x=\cfrac{83\cdot 10.5}{1}
\\\\\\
x=871.5~inches
\\\\\\
\textit{there are 12 inches in 1 foot, thus }
\\\\\\
871.5~\underline{in}\cdot \cfrac{ft}{12~\underline{in}}\implies 72.625~ft
\qquad \approx 73~ft[/tex]
