A researcher wants to test the difference in hours spent grading student work between junior and senior faculty. She assumes that junior faculty will spend more time grading student work than senior faculty. She selects at random 7 junior faculty and 7 senior faculty, and obtains an average of 15 hours/week for the junior faculty and 10 hours/week semester for the senior faculty. The variance for the junior faculty was found to be 3, for senior faculty, 1.

Do we reject the null hypothesis with a 95% level of confidence? Your answer should include stating the null and research hypothesis, your calculations, the t-ratio and the t critical value.