 That is the total revenue test. As we have studied up till now that the consumer demand is explained through the direct demand function and it can also be expressed through the inverse demand function. Then what is the utility of inverse demand function as we have studied already that it provides the opportunity to the entrepreneurs or to the businessmen or to the producers to assess the change in the price caused by the change in the quantity demanded. So, keeping in view that particular condition and including the responsiveness of the commodities to the price change, we can now assess that what is the significance of the elasticity of the demand. As the elasticity it measures the responsiveness of the quantity demanded to the price change. So, we see that the producer they are always in the want to enhance not only their output rather they want to improve their revenue and revenue will always be in a position not only to cover their cost rather minus cost that will provide the profit to the entrepreneurs. So, any businessman, producer or the entrepreneur, whenever he sees this, he wants to enhance his total revenue. And now when we say the total revenue it means that is equal to the total amount of the commodity produced by that producer supplied in the market and multiplied by the price which is the market price. So, if we say the price into Q of the market it will be the total revenue. So, now considering this we have studied up till now individual demand function when we totally aggregate the individual demand functions we come up with the market demand function. So, likewise the consumers demand function the market demand function it entails all the factors that we have already studied that the market demand of a commodity it depends upon the its own price it depending on the price of the other goods and at the same time it depends upon the income of the people who are going to purchase this. So, when we are having market demand curve on the basis of the individual demand curve from this market demand curve we can calculate the total market demand of that commodity. And then how this market demand can give any type of direction or the policy to the entrepreneur. So, the entrepreneurs can calculate the expected total revenue utilizing this demand function and utilizing the concept of price elasticity of demand. So, we can see that if a commodity is elastic it means the commodity is elastic is having the higher responsiveness to the smaller price change. So, it means the relative change in the quantity demanded is more in response to the smaller change in the price. So, if this is in the market scenario then the entrepreneur they must ensure that the small price increase it will cause more reduction in the quantity demanded. So, when there will be the larger reduction in the quantity demanded it means their product that will be kept mostly in the form of inventory and people they will not demand more. And when that will not be purchased more then the total revenue of that producer it will decline. So, this price elasticity it gives a complete policy line to the entrepreneur to decide about their price mechanism that up till which level they can have the change in their price mechanism. So, when is there is commodity whose elasticity we can say inelastic or relatively inelastic or we can say their responsiveness to the change in price is less than infinity but it is less than one. So, it is when it is the steeper curve we can say that whatever will be the change in the price either it can be increase or either it can be decrease. We can say if there will be small decrease in the price but that small change decrease it will enhance their consumers demand but not in that much quantity. Mean price decrease will be more but response in the quantity demanded that might be in the in the form of increase but that increase will be less and their total revenue will decline. So, consumers have a behavior that should be studied by the entrepreneurs. And entrepreneurs they will decide that any type of this small price decrease will reduce their total revenue. So, they should be very careful in that because in this form the consumer they will reduce their demand. So, a price increase and if there is any type of the price increase this price increase can be of any but that will increase the total revenue because due to this price increase now the consumer they have to reduce their demand but their reduction that will be of very nominal amount as a response to this price due to the less elasticity or the more inelastic nature. When there is unit elasticity it means whatever there will be the change in the price that change will be responded by the change in the quantity demanded. So, either there is increase or either there is decrease in the price it leaves the total revenue unchanged because the change in price is totally offset by the change in the quantity demanded. If price will increase then that will be responded by the decline in the quantity demanded and if price will decrease that may be increased. So, entrepreneur has to decide their price mechanism policy keeping in view the nature of the commodities.