| Class representative | 12 | 14 | 16 | 18 | 20 |
| Frequency | 5 | 7 | 10 | $a$ | 3 |
| (1) $4/\Lambda\Delta$ | (2) $4/9\Upsilon$ | (3) $\Delta/\Delta\Delta$ | (4) $\Delta/V4$ |
\textbf{142-} If the mean of grouped data equals 16, to determine the fourth class frequency, which value is correct?
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|}
\hline
Class representative & 12 & 14 & 16 & 18 & 20 \\
\hline
Frequency & 5 & 7 & 10 & $a$ & 3 \\
\hline
\end{tabular}
\end{center}
\begin{tabular}{llll}
(1) $4/\Lambda\Delta$ & (2) $4/9\Upsilon$ & (3) $\Delta/\Delta\Delta$ & (4) $\Delta/V4$
\end{tabular}
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