Line not equal length in table using cmidrule (tabularx)

Question

I found that the line is not the equal length in second row and the first row. Is it possible to make it same line length.

\documentclass{article}
\usepackage{tabularx, caption}           % Load package caption for decent foramtting and spacing
\usepackage{booktabs, ragged2e}       % Use booktabs rules and get rid og vertical rules, ragged2e to ragged text
\setlength\extrarowheight{1pt}          % Both line necessary for decent spacing, unless you are using booktabs rules.
\renewcommand{\arraystretch}{1.2}


\begin{document}

\newcolumntype{A}{>{\RaggedRight\arraybackslash\hsize=0\hsize\linewidth=\hsize}X}
\newcolumntype{B}{>{\RaggedRight\arraybackslash\hsize=0.65\hsize\linewidth=\hsize}X}
\begin{table}[!ht]

    \begin{tabularx}{\textwidth}{@{}A*{5}{B}@{}}
    \toprule
     & & \multicolumn{3}{c}{\textbf{ATest Combination}} \\
     \cmidrule(lr){3-5}
     & & \small Mean (\%)
     & \small Std. Deviation (\%)& \small Std. Error Mean(\%) \\
\midrule
    \multicolumn{1}{l}{Pair 1} & Transpor Example Dataset (AA) - Transpor Example Dataset (BB) 
    & 312314.20\% & 321321.36\% & 4.321354\%  \\
    \bottomrule
    \end{tabularx}
\caption{dsadsa dsadasd%
    \label{tab:test123}% 
    }  
\end{table}


\end{document}

The outcome:

And also, how to make the outcome of the word in whole words without being break out automaticall using '-'?

For example:

Transpor Example 
Dataset (AA) - 
Transpor Example 
Dataset (BB)

and not

Transpor Exam-
ple Data -
set (AA) - 
Trans- 
por Example 
Dataset (BB)

Answer 1

Here are three different versions of your table:

In all of the following example, I have corrected the trimming commands of the cmidrule command ((lr), (l), (r), For a detailed explanation please see page 4 of the booktabs manual.)

In the first example, I have also replaced the column specifiers {@{}A*{5}{B}@{}} by the more reasonable {l>{\raggedright\arraybackslash}Xccc}.

In the second table, I have alternatively used S type columns from the siunitx package in order to allow the numbers to be centered with respect to their decimal separator. Additionally, I have removed repeated % signs that are superfluous since they are already mentioned in the column headers.

In the last example, I have used a slightly smaller font size and decreased the horizontal white space between adjacent columns. With this, the contents of the second column can even fit into two lines instead of 4.

\documentclass{article}
\usepackage{tabularx, caption}
\usepackage{booktabs, ragged2e}

\usepackage{makecell,siunitx}

\begin{document}

\begin{table}

    \begin{tabularx}{\textwidth}{l>{\raggedright\arraybackslash}Xccc}
    \toprule
    & & \multicolumn{3}{c}{\textbf{ATest Combination}} \\
     \cmidrule{3-5}
     & & \small Mean (\%)
     & \makecell{\small Std. Deviation\\ (\%)}& \makecell{\small Std. Error \\ Mean (\%)} \\
\midrule
    \multicolumn{1}{l}{Pair 1} & Transpor Example Dataset (AA) - Transpor Example Dataset (BB) 
    & 312314.20\% & 321321.36\% & 4.321354\%  \\
    \bottomrule
    \end{tabularx}
\caption{dsadsa dsadasd%
    \label{tab:test123}% 
    }  
\end{table}

\begin{table}
    \begin{tabularx}{\textwidth}{l>{\raggedright\arraybackslash}XS[table-format=6.2]S[table-format=6.2]S[table-format=1.6]}
    \toprule
    & & \multicolumn{3}{c}{ATest Combination} \\
     \cmidrule{3-5}
     & &  {Mean (\%)}
     & {\makecell{ Std. Deviation\\ (\%)}}& {\makecell{ Std. Error \\ Mean (\%)}} \\
\midrule
    \multicolumn{1}{l}{Pair 1} & Transpor Example Dataset (AA) - Transpor Example Dataset (BB) 
    & 312314.20 & 321321.36 & 4.321354  \\
    \bottomrule
    \end{tabularx}
\caption{dsadsa dsadasd%
    \label{tab:test123}% 
    }  
\end{table}

\begin{table}
\small \setlength{\tabcolsep}{3.5pt}
    \begin{tabularx}{\textwidth}{l>{\raggedright\arraybackslash}Xccc}
    \toprule
    & & \multicolumn{3}{c}{ATest Combination} \\
     \cmidrule{3-5}
     & &  Mean (\%)
     & \makecell{ Std. Deviation\\ (\%)}& \makecell{ Std. Error \\ Mean (\%)} \\
\midrule
    \multicolumn{1}{l}{Pair 1} & Transpor Example Dataset (AA) - Transpor Example Dataset (BB) 
    & 312314.20 & 321321.36 & 4.321354  \\
    \bottomrule
    \end{tabularx}
\caption{dsadsa dsadasd%
    \label{tab:test123}% 
    }  
\end{table}




\end{document}