Final answer:
To format the Markup column as percentages in Excel, select the cells, right-click to open 'Format Cells', choose 'Percentage', set decimal places, and click 'OK'.
Step-by-step explanation:
To format data in the Markup column to display as percentages in an Excel worksheet, you need to select the cells in the Markup column that you want to format. Once selected, right-click and choose 'Format Cells' from the context menu. Then, in the Format Cells dialog box, click on the 'Number' tab and select 'Percentage' from the list of categories. You can also specify the number of decimal places you want to display. Finally, click 'OK' to apply the formatting. This process changes the display format of the cells in the Markup column so that numbers are interpreted as percentages, with each value multiplied by 100 and displayed with a percent symbol (%).