A researcher is interested in whether juniors and seniors spend the same amount of time socializing in a week.She selects at random 40 juniors and 40 seniors, and obtains an average of 10 hours for the juniors, and 20 hours for the seniors.The standard deviation of the sampling distribution of differences between means (_{X1 - X2}) is 5. Do we reject or accept the null hypothesis, with a level of confidence of 95%?

Here you should include your calculations, as well as your final answer. The answer should include: null and research hypotheses, all relevant calculations, relection region, final decision (to accept or reject the null hypothesis.)