Tell whether the ratios form a proportion.

1. [tex]\frac{17}{20}[/tex], [tex]\frac{90.1}{106}[/tex]

2. [tex]\frac{3.2}{4}[/tex], [tex]\frac{16}{24}[/tex]

3. [tex]\frac{34}{50}[/tex], [tex]\frac{6.8}{10}[/tex]