. Use the tdistribution to find a confidence interval for a mean given the relevant sample results. Give the best estimate for , the margin of error, the appropriate degrees of freedom, and the confidence interval. Assume the results come from a random sample from a population that is approximately normally distributed. A 90% confidence interval for using the sample results x = 3.1, s = 0.4, n = 100, and given that t = 1.660.