Examples when demand may have got out of a hand?

Recall, that we represent economic laws and theory using models; in this case we can use a demand schedule or a demand curve to illustrate the Law of Demand.  The demand schedule shows the combinations of price and quantity demanded of apples in a table format.  The graphical representation of the demand schedule is called the demand curve

When graphing the demand curve, price goes on the vertical axis and quantity demanded goes on the horizontal axis. A helpful hint when labeling the axes is to remember that since P is a tall letter, it goes on the vertical axis. Another hint when graphing the demand curve is to remember that demand descends.

The demand curve reflects our marginal benefit and thus our willingness to pay for additional amounts of a good.  It makes sense that our marginal benefit, or willingness to pay for a good, would decline as we consume additional units because we get less additional satisfaction from each successive unit consumed. For example, at lunch time you decide to buy pizza by-the-piece.  You'd be willing to pay a lot for that first piece to satisfy your hunger.  But what about the second piece?  Perhaps a little less.  If we keep considering each additional piece, we might ask what the 3rd, 4th or 5th piece is worth to you.  By that point, you'd be willing to pay less, perhaps much less.  The law of demand and our models illustrate this behavior.

Explanation:

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