Answer: 600 mm
Step-by-step explanation:
Let height of her model be x meters
So,
500x = 300
[tex]\begin{aligned}&\rightarrow x=\frac{300}{500} \\&\rightarrow x=\frac{3}{5}=0.6 \text { meters } \\&\rightarrow x=0.6 \times 1000 \text { millimeters } \\&\rightarrow x=600 \text { millimeters }\end{aligned}[/tex]
Therefore, Stacy's model is 600 millimeters tall
