Am having issues finding the formula to used sine I have A STUDENTS AND B STUDENTS with just this amount of information sine the data is 700 students can some one help me understand how to find the correct way. I did the fist part sine is finding the A and B students but when I break it apart to find the sample mean excel show that am making an error by no counting all the cells while using the =average formula. So it goes like A......A then it changes to B....B so I don't known how to work this problem

1) In the first part of this project, you want to test if, before the introduction of caloric labeling, the daily caloric intake by students dining in dining halls A and B was indeed similar. To do this, start by calculating the number of students surveyed at each dining hall. In cell F2, input the number of students surveyed in dining hall A; in cell G2, input the number of students surveyed in dining hall B. (HINT: use the COUNTIF function in Excel). Calculate sample mean of the caloric intake for students dining in A and B. Input your results in cells F3 and G3 respectively. Calculate the observed sample variance of the caloric intake for students dining in A and B. Input your results in cells F4 and G4 respectively. (Use the VAR.S function in Excel). \begin{tabular}{|l|l|r|r|} \hline & \multicolumn{1}{|c|}{ A } & \multicolumn{1}{c|}{ B } & \multicolumn{1}{c|}{ C } \\ \hline 1 & Dining hall Calories be Calories aft \\ \hline 2 & A & 2909.527 & 2075.756 \\ \hline 3 & A & 2319.78 & 1565.201 \\ \hline 4 & A & 2424.375 & 2026.329 \\ \hline 5 & A & 2472.93 & 1516.399 \\ \hline 6 & A & 2904.577 & 1660.427 \\ \hline 7 & A & 2869.392 & 1692.215 \\ \hline 8 & A & 2614.903 & 2009.231 \\ \hline 9 & A & 2895.96 & 2306.358 \\ \hline 10 & A & 2818.561 & 2834.176 \\ \hline 11 & A & 2806.505 & 2131.587 \\ \hline 12 & A & 3191.462 & 1555.507 \\ \hline 13 & A & 2329.117 & 2496.986 \\ \hline 14 & A & 2979.254 & 2042.796 \\ \hline 15 & A & 2478.189 & 1949.191 \\ \hline 16 & A & 3023.695 & 2231.312 \\ \hline 17 & A & 2452.423 & 2359.287 \\ \hline 18 & A & 2843.396 & 1904.354 \\ \hline 19 & A & 3257.542 & 1837.717 \\ \hline 20 & A & 2817.13 & 2619.459 \\ \hline \end{tabular}