T-Distribution 1. Find the t-value to the left of the mean for a=1 and n=11 2. Construct a 99% confidence interval for a population mean if we have a sample mean of 67.5, a sample standard deviation of 8.3, and n=7 3. What is the t-value of the distribution with a=1 and n=18 under the one-tailed test? 4. What is the area under the t-distribution from t= -1.771 to t=2.160 at df=13