Final answer:
The default tab that is active when you open a Microsoft Office application is the Home tab, which houses common editing tools.
Step-by-step explanation:
When you open a Microsoft Office application, the Home tab on the Ribbon is active by default. This tab contains the most frequently used commands such as font formatting, paragraph alignment, and text styling. It is the primary location where you can find general tools for editing your document. To solve this, we can set up a ratio since the number of commercials is directly proportional to the amount of TV time. If 30 commercials are in 2 hours, we divide 30 by 2 to find out how many commercials are aired per hour, which is 15 commercials per hour.