What denominator for 2/13 = 49/? would make these ratios proportional?
To make the ratios proportional, the denominators must be equivalent. In this case, we have the proportion $\frac{2}{13}=\frac{49}{x}$. To solve for $x$, we can cross-multiply: \begin{align*}
2x &= 13 \cdot 49 \\
2x &= 637 \\
x &= \frac{637}{2}.
\end{align*} Therefore, a denominator of $\boxed{\frac{637}{2}}$ would make the ratios proportional.