[tex]\bf \cfrac{model}{actual}\qquad 1:300\qquad \cfrac{1}{300}\qquad \qquad \cfrac{3\frac{1}{2}}{a}=\cfrac{1}{300}\implies \cfrac{\frac{3\cdot 2+1}{2}}{a}=\cfrac{1}{300}
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\cfrac{\quad \frac{7}{2}\quad }{a}=\cfrac{1}{300}\implies \cfrac{\quad \frac{7}{2}\cdot 300\quad }{1}=a\implies 1050=a[/tex]