I am stuck and would love an explanation how you get the answers for this. Can you please use Excel to answer this question and show the Excel formulas you used:

A study looked at n=256 adolescents, where subjects wore a wrist actigraph, which allowed the researchers to estimate sleep patterns. Those subjects classified as having low sleep efficiency had an average systolic blood pressure that was 5.6 millimeters of mercury (mm Hg) higher than that of other adolescents. The standard deviation of this difference is 1.8 mm Hg. Based on the results, test whether this difference is significant at the 0.01 level