Problem
i. What is the formula used to calculate degrees of freedom? What are the degrees of freedom for a sample size of 25?
ii. Suppose the mean score for the critical reading test cited in the previous question is 580. What is the probability that a random sample of 500 students will have a mean score of more than 590?
iii. Based upon extensive data from a national high school educational testing program, the standard deviation of national test scores for critical reading was found to be 115 points. If a sample of 500 students are given the test, what would be the standard error of the mean?