Rumble, Grumble When David is hungry, he gets grouchy. When he isn't hungry, he stays in a good mood. In other words, David's mood is a function of his hunger level. David's friend Karla usually has positive feelings toward him. But when he is grouchy, Karla gets irritated with him. In other words, Karla's attitude toward David is a function of his mood. Assume David eats three meals a day, at regular times, so that his hunger level is a function of the time of day. Sketch a graph of Karla's feelings toward David as a function of time over the course of two days.