The television would be set to channel&29, given that it was set to channel 30 and then channelDown was invoked after that.

The television would presumably set to a volume of 7. Going back to the initial state, it had a volume of 5. After first call to volumeUp, it has volume of 6. Then it is muted. Internally, it still remembers that it has a volume of 6, even though it is currently muted. The final call to volumeUp would raise the volume to 7 and, for a typical television, unmute the television automatically.

There is not a particular "right" answer, but we are looking for a reasonable model that captures notions of a two-dimensional physics simulator, such as having attributes like xPosition, yPosition, xVelocity, yVelocity, and perhaps mass, elasticity, and so on.

Behaviors would presumably include those that access or update the position and velocity, and perhaps higher-level concepts such as bounce.