A Random Sample of Magnesium Concentrations (In Parts Per Million $90 \%$

Multiple Choice

A random sample of magnesium concentrations (in parts per million, or ppm) in ground water from various locations follows. Estimate the mean concentration of magnesium in ppm with $90 \%$ confidence. Assume $\sigma = 20$ .
$\begin{array} { c c c c c } 44 & 122 & 34 & 114 & 5 \\ 101 & 68 & 106 & 100 & 56 \\ 42 & 66 & 36 & 20 & 18 \\ 98 & 101 & 28 & 89 & 100 \\ 125 & 7 & 31 & 94 & 21 \\ 70 & 38 & 18 & 60 & 18 \\ 98 & 51 & 30 & 120 & 68 \end{array}$

A) $56.1 < \mu < 69.4$
B) $57.2 < \mu < 68.3$
C) $59.4 < \mu < 66.2$
D) $61.8 < \mu < 63.7$