A researcher thinks that listening to classical music reduces anxiety. She measures the anxiety of 10 persons then plays Mozart's "Eine Kleine Nachtmusik". Following that the researcher measures their anxiety again. (Note that anxiety is measured on a scale from 1 to 7, with higher numbers indicating increased anxiety.)

Does the study support her hypothesis? Compute the upper bound of the confidence interval using the following data:

mean of the difference scores (subtract pretest from posttest): -1.3

standard error of the difference scores: 0.6

The formula for the CI upper bound is [standard error of the difference scores]*[t critical value]+[mean of the difference scores]

How do you put this in to the formula and what is the formula. How do you find the t critical value?