2. Use Excel functions \\( \\left(\\boldsymbol{f}_{\\boldsymbol{x}}\ ight) \\) to answer questions a. to \\( \\mathbf{c} \\) : a. What is the average income of the subgroup noncitizens? b. What is the difference between the average income of the subgroup citizens and the subgroup noncitizens? c. Is the difference between the average income of the subgroup citizens and the subgroup noncitizens statistically significant? Explain in the space below