| Data | 11 | 12 | 13 | 14 | 28 | 31 | $a$ |
| Frequency | 3 | 2 | 6 | 3 | 2 | 5 | 1 |
\textbf{128-} In the frequency table below, the median is $13.5$ and the first quartile minus the third quartile is $17$. If we add $4$ units to each data value in the table, what is the new variance?
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\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|}
\hline
Data & 11 & 12 & 13 & 14 & 28 & 31 & $a$ \\
\hline
Frequency & 3 & 2 & 6 & 3 & 2 & 5 & 1 \\
\hline
\end{tabular}
\end{center}
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(1) $71$ \hfill (2) $71.5$ \hfill (3) $72$ \hfill (4) $72.5$
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