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
o=14
117 67 71 90 89
72 93 38 104 23
6 14 115 88 15
78 122 68 118 71
99 93 43 15 57
18 8 56 48 124
66 59 107 30 6