 11, marginal utility. Marginal utility is an important concept in economics. The concept of marginal utility in fact explains the change in total utility because of increase in consumption of that particular commodity. In fact, it explains the addition in total utility due to consumption of an additional unit of the commodity. For example, if someone is using apples, whenever an additional unit of apple is consumed by that consumer, it results a change in total utility. That change in total utility because of additional unit of apple is called as marginal utility. So, the word marginal and change are synonym in economics. And to measure marginal utility, we usually divide change in utility with change in quantity, change in quantity under consideration. For example, if our objective is to compute marginal utility of oranges, then it indicates change in utility because of change in quantity of oranges. And here this delta sign indicates a change in value. Again, if we consider the table where first column indicates the quantity of oranges, second column indicates the total utility that someone is getting from the quantity of oranges and the third column is reporting the marginal utility. Here, marginal utility we compute by subtracting the previous unit's total utility from current total utility. The change in utility is in fact change in utility between two quantities of oranges. For example, if consumer moves from 0 unit of orange to 1 unit of orange, his total utility moves from 0 to 20. So, change in utility when consumer increase the consumption of oranges from 0 to 1 is equal to 20. And similarly, when consumer again use an additional unit of orange against two units of oranges, total utility of the consumer is equal to 30. While total utility against the first unit of oranges is equal to 20. So, in this case, marginal utility is equal to 10. That is addition in total utility because of additional consumption of a commodity. We can see up to unit 11, marginal utility is positive, but against 11th unit of orange, marginal utility becomes 0. So, here the and after 11th unit of oranges, marginal against 12th unit of orange, marginal utility becomes negative. This negative is because of the reason against 11th unit of orange, consumer is getting a utility is equal to 74. While against 12th unit of orange, consumer is getting a utility is equal to 70. So, the difference between these two points is equal to minus 4. So, against 12th unit of orange, utility is equal to minus 4. In the computation of the marginal utility, point of saturation plays an important role. If we report all these things graphically, we can see marginal utility up to unit 11 is equal to 11 is greater than 0. But after against 11th unit of orange, marginal utility is equal to 0 while if someone is using more than 11 units of oranges, his marginal utility becomes negative. And this negative value of the values of the marginal utility is greater than 0 is equal to 0 or less than 0. It depends upon the point of saturation. Marginal utility of the consumer is positive as long as consumer has appetite for the oranges. That is before the saturation point, the consumer is not fully saturated with the consumption of oranges. And this value of marginal utility is 0 when the consumer has no appetite for oranges, but still he is using that orange. And because of usage of that additional quantity of orange, he is at the point of saturation, but his marginal utility is equal to 0. But after reaching the point of saturation, if there is still consumer is using commodity consistently, then his marginal utility becomes negative. So, forced consumption of oranges when he has no appetite for the consumption of oranges, then marginal utility becomes negative. In this diagram, again we are reporting total utility and marginal utility. As long as marginal utility increases, as long as total utility of the consumer increases, marginal utility is positive. By looking at these two graphs of total utility and marginal utility, we can have a, we can develop an association between total utility and marginal utility. And marginal utility is a very important concept. And as we have already discussed in this module, marginal utility is changed in total utility because of change in consumption of the commodity under consideration.