A random sample of 25 items is drawn from a population standard deviation is unknown. The sample X=830 and the Standard deviation is S=5.(find the values of students t) a) construct an interval estimate of U with 95% confidence(round your answer to three decimal place) b) construct an interval estimate of U with 95% confidence assuming that S=10 c) construct an interval estimate of U with 95% confidence assuming that S= 20