Answer
Your Sigma Apple Pi, Tri Deltoids, Alpha Beta Chi, and Totals worksheets should look like so:

To download the complete answer key, click the link below:
Explanation
1. Open the "Excel Cram Kit (Test #2) - Multiple Sheets.xlsx" file.
Click on and open the designated file. Your screen should have the following spreadsheet up after doing so:

2. Select the Sigma Apple Pi sheet and then group all 3 worksheets (Sigma Apple Pi through Alpha Beta Chi). Then, complete the following:
- Auto Fill the rest of the "Day _" values in A4:A6 so that the row titles contain Day 1, Day 2, and Day 3.
- In row 7 use the SUM function to compute the total recruits that hung out in each room during Meet the Brothers. Then, in column E do the same for each of the days. Make sure to include an overall total in cell E7.
- Format B4:E7 to have a dotted inner border. (HINT: Make sure to check out the "More Border Options")
- Format A3:E7 to have Thick Box Border.
To group all 3 worksheets, all we need to do is click on the Sigma Apple Pi worksheet and then while holding the Shift key, click on the Alpha Beta Chi worksheet.

Notice how now, all 3 worksheets are highlighted. This means that we've successfully grouped them!
Next, let's complete each bullet point, starting with Auto Filling the rest of the day values in A4:A6. To do this, click on the A4 cell and then click and hold the green little box in the bottom right corner. Drag this through to A6.

Now that we've got the Days successfully Auto Filled, let's move onto computing the total number of recruits in each room. To do so, in cell B7, write the following SUM function:
=SUM(B4:B6)

Now, drag this through to D7.

Next, let's do the same for each day. In cell E4, type the following SUM function:
=SUM(B4:D4)

Then, drag this through to E7. This enables us to compute the total number of recruits per day, and additionally the total number of recruits in all (within cell E7).

Next, let's format B4:E7 to have a dotted inner border. To do so, highlight the cells and in the border dropdown, select "More Borders...".
Within the pop-up window, click the dotted line style, then select the middle horizontal and middle vertical border options.

Lastly, we need to format A3:E7 to have a Thick Box Border. Simply highlight those cells, and in the borders dropdown select "Thick Box Border".

3. Ungroup the worksheets and ensure that your formatting was applied to all of them.
Click on Tri Deltoids worksheet, and then Alpha Beta Chi worksheet. Notice how they're formatted the same as Sigma Apple Pi? That means we successfully grouped our worksheets and applied the same formatting to each one!
