prevent the price of a product from falling below the level. For example, The graph 1show the price above is600 dollars. However, most people cannot afford this price,so government reduce it to 400 dollars . That would make it affordable for mostpeople. The graph 2 show the price bottom is 8 dollars . However, with thedevelopment of time and economy, 8 dollars has been much lower than the normalprice, so government need to increase it to 12 dollars. We can think of graph 1 asrent and graph 2 as