The following MINITAB output presents a confidence interval for a population mean.
$\begin{array}{crrrcc}
\hline \text { Variable } & \mathrm{N} & \text { Mean } & \text { StDev } & \text { SE Mean } & 99 \% \text { CI } \
x & 30 & 89.4928 & 33.3397 & 6.0870 & (72.693,106.293) \
\hline
\end{array}$
Find the critical value $t _ { \alpha / 2 }$ for a $98 \%$ confidence interval.
A) 2.462
B) 2.750
C) 2.760
D) 2.457

Question

Quizplus · Accepted Answer

The critical value $t _ { \alpha / 2 }$ for a 98% confidence interval with 29 degrees of freedom (since $N = 30$) is closest to 2.462, which can be found in t-distribution tables or using statistical software for the 99% confidence level (since the question mistakenly asks for 98% but provides data for 99%).

The Following MINITAB Output Presents a Confidence Interval for a Population