# why does \hline produce different thickness lines [closed]

I am new to LaTeX and so still learning. I am using the following code and am surprised to get the middle horizontal line in bold. Any help would be appreciated.

 \begin{table}[htbp]
\centering
\caption{Average Returns for Three Years Following the Stock's Listing}
\resizebox{\textwidth}{!}{\begin{tabular}{rrrccccc}
\hline
&       &       & First 6 months & Second 6 moths & First Year & Second Year & Third Year \\
\hline
IPO Firms &       &       & 144\% & 5.00\% & 152\% & 9.00\% & 5.00\% \\
Size-matched Firms &       &       & 8\%   & 6.00\% & 17\%  & 16\%  & 7.00\% \\
\textit{t}-statistics for difference &       &       & 2.03  & -0.41 & 1.8   & -1.09 & -0.21 \\
Sample Size &       &       & 115   & 115   & 115   & 115   & 105 \\
\hline
\end{tabular}}
\label{tab:returns}%
\end{table}%


## closed as unclear what you're asking by TeXnician, moewe, Troy, Torbjørn T., CarLaTeXMay 21 '17 at 15:49

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• Hi ! Could you give us a compilable sample of code ? – flav Mar 18 '16 at 7:02
• Are you sure it's not a viewer problem? Did you print the result? – Ignasi Mar 18 '16 at 7:32
• most likely it is just your viewer snapping to an integer number of pixels, but scaling tables \resizebox{\textwidth}{!}{ doesn't help that effect (and leads to inconsistent font sizes with the rest of the document) – David Carlisle Mar 18 '16 at 7:47