33. Suppose the shoe sizes of five students were recorded as 7.5, 9, 6, 5, 11. Calculate by hand a 90% confidence interval for the unknown mean u using the test statistic t. Recall that X-H s/vn has a t -distribution with n - 1 degrees of freedom. Table A.2 Upper Percentiles of Student t Distributions Student / distribution with df degrees of freedom Area = 0 0 a. df df 0.20 0.15 0.10 0.05 0.025 0.01 0.005 1.376 1.963 3.078 6.3138 12.706 31.821 63.657 2 1.061 1.386 1.886 2.9200 4.3027 6.965 9.9248 3 0.978 1.250 1.638 2.3534 3.1825 4.541 5.8409 4 0.941 1.190 1.533 2.1318 2.7764 3.747 4.6041