 Consumer behavior and under this chapter we are going to study the marginal utility. What we mean by the marginal utility and why we study the marginal utility? When we say the consumer is going to gain the utility from the utilization of either any good or a service then definitely there will be certain conditions when this will change. So, how this utility will change and if this utility the level of satisfaction that the consumer has gained to the attainment of certain good and the service is going to change, either this change will be equal for each type of commodity or it may vary. And if it is like this, what will be the level or the rate of the change? So, when we say the marginal utility, we mean that this is the rate at which utility of a consumer changes mostly consumer is going to utilize not a single commodity rather consumer prefers to utilize a bundle of the commodity up till now we have studied mostly a bundle that is having two commodities at least so we can depict one on x-axis and the other on y-axis. So, in that our example when a consumer is having two commodities on which we are taking commodity x1 on the x-axis and now we assume that for one unit change in the consumption of good x1 what will be the change in the total utility of the consumer? So, what will be the change in the total utility with one additional unit of the commodity x1 that the commodity is going to be attained by the consumer? We may hear by the rate that marginal utility as we have shown here it is the change in the utility with respect to the change in commodity x1 for which we are going to assess its marginal utility and here it is the utility attained by the consumer for one additional unit minus the utility that the consumer was having with the previous unit. So, with this formula we can say that marginal utility basically it will be like this when we say it is change in utility due to change in x and that is why when we multiply by this marginal utility with the change we can say that it is the change in the consumption that the consumer has gained through the change in the marginal utility and the rate in the change is called the marginal utility but at this point we are not going to change the commodity on the y-axis so the marginal utility will be made keeping the other commodity constant and the marginal utility is the change in utility associated with the change in the consumption of good too. So, here we will say if we have to measure with respect to other commodity again the same formula will be utilized and likewise if we can utilize the same method for a multiple good case we can calculate the marginal utility of the consumer for each unit of the commodity and for each commodity in the long run. The concept of marginal utility is very much important not only for the consumer but also for the assessment of the many other methods. Consumer when will have the awareness and the knowledge related to the marginal utility of the various commodities it will be possible for him to compare the various commodities with reference to its marginal utility. So, for one unit of the commodity if consumer will have the proper measurement then he will be able to pay or he will be able to prefer that commodity for which he can have more utility for one unit of the price or for one unit of the attainment. So, the concept of marginal utility is not only important for the consumer but also for the study of the consumer behavior and here one more point that is very much important that this marginal utility it depends upon the magnitude of the total utility or the utility. If the consumer is already having the utility of the 15. So, for one unit change its marginal utility will be somewhat less but if he is starting from the 3 and going to 4 so the base is different so here it will be somewhat different. So, the utility and its magnitude is very much important and for this magnitude measurement we need to measure the utility. Thank you.