Compute the duration for the data in this problem using a discount rate of 12%.

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\begin{tabular}{|c|c|} \hline & Cash \\ \hline Year, t & Flow \\ \hline 1 & 90 \\ \hline 2 & 90 \\ \hline 3 & 90 \\ \hline 3 & 1000 \\ \hline \end{tabular}