The Time It Takes to Complete a Test Was Recorded $$\begin{array} { l l l l l } 25 & 45 & 50 & 32 & 38 \\41 & 41 & 48 & 30 & 40 \\39 & 49 & 46 & 44 & 36\end{array}$$

Essay

The time it takes to complete a test was recorded for a sample of 15 students. The results follow. $$\begin{array} { l l l l l } 25 & 45 & 50 & 32 & 38 \\41 & 41 & 48 & 30 & 40 \\39 & 49 & 46 & 44 & 36\end{array}$$ Use Excel to estimate the variance with a 90% level of confidence.