find out the lower point of the 90 percent confidence interval for mean.
For a sample of 11 independent observations from a normal distribution of unknown μ and unknown variance σ^{2}, the sample mean is 74.60 and sample variance is 2.2. What is the lower point of the 90 percent confidence interval for μ?
(1) 73.1206
(2) 72.8469
(3) 73.7896
(4) 73.9863
(5) 73.1167