A random sample of 64 observations has a mean of 30. The population variance is assumed to be 9. The 85.3% confidence interval estimate for the population mean (to the third decimal place) is: $\begin{array}{|l|l|}
\hline\text { A. } & 28.369 \pm 31.631 . \
\hline \text { B. } & 29.456 \pm 30.544 . \
\hline \text { C. } & 28.560 \pm 31.440 . \
\hline \text { D. } & 29.383 \pm 30.617 . \
\hline
\end{array}$

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The Answer of A random sample of 64 observations has a mean of 30. The population variance is assumed to be 9. The 85.3% confidence interval estimate for the population mean (to the third decimal place) is: $\begin{array}{|l|l|}
\hline\text { A. } & 28.369 \pm 31.631 . \
\hline \text { B. } & 29.456 \pm 30.544 . \
\hline \text { C. } & 28.560 \pm 31.440 . \
\hline \text { D. } & 29.383 \pm 30.617 . \
\hline
\end{array}$

A Random Sample of 64 Observations Has a Mean of 30