Marginal costs are a central component of a firm's costs structure. What are other situations where marginal values exist? Some examples might be the increase in income from one more hour of work, the change in speed when you step on a car's accelerator pedal, and the increase in grades in this course per hour of studying. What do you think these marginal curves look like? Are they all upward sloping? For example, do you expect your grade to go up the same amount if you increase your studying 8 to 9 hours per week as if you increase your studying from 15 to 16 hours per week? Provide at least one example of a marginal value and present an argument as to whether its curve is upward sloping, constant, or downward sloping.