2. A researcher wants to test the differences in the number of hours freshmen and seniors spend engaging in extra-curricular activities in a week. She selects at random 25 freshmen and 25 seniors, and obtains a mean of 2 hours/week for the freshmen and 7 hours/week for the seniors. The standard deviation of the sampling distribution of differences between means (oxi ->2) is 1.5. Do we reject or accept the null hypothesis, with a level of confidence of 95%