Mr. Grava tee spends most Sunday afternoons at rest on the sofa, watching pro football and eating large quantities of food. What effect, if any, does this have on inertia?

This will increase his inertia.

Explanation:

Inertia is the resistance of any object to any variation in its state. Since inertia is directly proportional to its mass, it means that the object having greater mass would have greater inertia. As Mr. Grava tee spends most Sunday afternoons at rest on the sofa, watching pro football and eating large quantities of food, so this act is increasing his mass and as well as his inertia.