To compare the fractions \( \frac{3}{10} \) and \( \frac{7}{10} \) using the number line:
- The number line you described has 10 equal spaces between 0 and 1, which means each space represents \( \frac{1}{10} \).
- Therefore, \( \frac{3}{10} \) is located at the 3rd space on the number line (0.3), and \( \frac{7}{10} \) is located at the 7th space on the number line (0.7).
Since \( 0.3 < 0.7 \), we can conclude that:
\[ \frac{3}{10} < \frac{7}{10} \]
Thus, the correct statement is:
\( \frac{3}{10} < \frac{7}{10} \).