A random sample of n = 15 items is taken, producing a sample mean ofx = 10 with a sample variance ofs=2.5. Assume x is normally distributed and construct a 90% confidence interval for the population mean .

a.

Lower Confidence Limit (L.C.L) = 12.33 Upper Confidence Limit (U.C.L) = 10.67

b.

Lower Confidence Limit (L.C.L) = 9.33 Upper Confidence Limit (U.C.L) = 12.67

c.

Lower Confidence Limit (L.C.L) = 9.33 Upper Confidence Limit (U.C.L) = 10.67

d.

Lower Confidence Limit (L.C.L) = 10.33 Upper Confidence Limit (U.C.L) = 10.67