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If the last T-shirt provides more than twice the marginal utility of the last movie, then the T-shirt is providing more “bang for the buck” or marginal utility per dollar, than if the money were spent on movies. As a result, José should buy more T-shirts. Notice that at José’s optimal choice of point S, the marginal utility from the first T-shirt, of 22 is exactly twice the marginal utility of the sixth movie, which is 11. At this choice, the marginal utility per dollar is the same for both goods. This is a tell-tale signal that José has found the point with highest total utility.

This argument can be written as a general rule: the utility-maximizing choice between consumption goods occurs where the marginal utility per dollar is the same for both goods.

MU 1 P 1 = MU 2 P 2

A sensible economizer will pay twice as much for something only if, in the marginal comparison, the item confers twice as much utility. Notice that the formula for the table above is:

22 $14 = 11 $7 1.6 = 1.6

The following Work It Out feature provides step by step guidance for this concept of utility-maximizing choices.

Maximizing utility

The general rule, MU 1 P 1 = MU 2 P 2 , means that the last dollar spent on each good provides exactly the same marginal utility. So:

Step 1. If we traded a dollar more of movies for a dollar more of T-shirts, the marginal utility gained from T-shirts would exactly offset the marginal utility lost from fewer movies. In other words, the net gain would be zero.

Step 2. Products, however, usually cost more than a dollar, so we cannot trade a dollar’s worth of movies. The best we can do is trade two movies for another T-shirt, since in this example T-shirts cost twice what a movie does.

Step 3. If we trade two movies for one T-shirt, we would end up at point R (two T-shirts and four movies).

Step 4. Choice 4 in [link] shows that if we move to point S, we would lose 21 utils from one less T-shirt, but gain 23 utils from two more movies, so we would end up with more total utility at point S.

In short, the general rule shows us the utility-maximizing choice.

There is another, equivalent way to think about this. The general rule can also be expressed as the ratio of the prices of the two goods should be equal to the ratio of the marginal utilities. When the price of good 1 is divided by the price of good 2, at the utility-maximizing point this will equal the marginal utility of good 1 divided by the marginal utility of good 2. This rule, known as the consumer equilibrium    , can be written in algebraic form:

P 1 P 2 = MU 1 MU 2

Along the budget constraint, the total price of the two goods remains the same, so the ratio of the prices does not change. However, the marginal utility of the two goods changes with the quantities consumed. At the optimal choice of one T-shirt and six movies, point S, the ratio of marginal utility to price for T-shirts (22:14) matches the ratio of marginal utility to price for movies (of 11:7).

Measuring utility with numbers

This discussion of utility started off with an assumption that it is possible to place numerical values on utility, an assumption that may seem questionable. You can buy a thermometer for measuring temperature at the hardware store, but what store sells an “utilimometer” for measuring utility? However, while measuring utility with numbers is a convenient assumption to clarify the explanation, the key assumption is not that utility can be measured by an outside party, but only that individuals can decide which of two alternatives they prefer.

Questions & Answers

type of goods and services
Nesar Reply
There are two types of goods which are capital and consumer goods
Muafue
what is microeconomics
Mahmood
micro-economics is the study of how firms and households make decisions and how they interact
Saadaq
discuss separately how scarcity arises for house holds, business and government
Hawa
who gave the concept of perfect competition in economics?
Sandeep Reply
 Léon Walras gave the first definition of perfect competition   
ADITYA
no, it was me😂
Nancy
What is Indifference curve?
Ch
Perfect competition is an idealized market structure that achieves an efficient allocation of resources.
Daauud
what are the conditions for determining the nature of goods in partial differentiation
Unique
what is economics
Arman Reply
is a science which study human behaviour as relationship between ends and scarce means hav altenative uses
Herieth
what are the other factors of demand
Aysher Reply
what are other factors in demand
Aysher
What is price elasticity of demand
Ghulam Reply
ok
debashis
what makes a country to be operating within the PPC
The Reply
two different product that are being are being produced efficiently
Othusitse
what is quartile
sukhdeep Reply
quartile occurs as a numerical probabilistic aspect such as quartile 1,2 or 3.
Othusitse
what will happen ifvwe will increase the price
Harleen Reply
due to increase the price the demand redeuce to related product
abdullah
the higher the price leads to low quantity to be demanded
Herieth
what is demand change
George
When price of any commodity change than demand is automatically change. Prince and demand have direct relationship.
Ch
what is long run?
Cabdulahi Reply
what will be the price
Harleen Reply
how the price determined in oligopoly?
Sahil Reply
what are the main problems in the market!?
Baby Reply
Price effect is a combination of income and substitution effect discuss
saroj Reply
Randy how IC energetic is superior to utilise energetic
saroj
why economics is undependent subject?
Yohanissy Reply
Why?
Ch
What's the scope of Economic?
Ch
What's Economic scope?
Ch
what is c.s p.s and market efficency
Raghu
what is scope of economics
Herieth Reply
Scope of economic?
Ch
it consist of *subject matter of economics *normative and positive *economics problem solving * science and arts
Herieth
A few days ago i get admission in MS.C economic. How i grip it?
Ch
in which university you take admission?
Shoaiq
I get admission in a acadme.And that is relevate with Peshawar university.
Ch
Pertinent bro
Muafue
Did anybody have Macroeconomic nd Microeconomic's'notes?
Ch
how economics is a particular kind of economising!?
Baby
i hav notes of microeconomics
Herieth
human touch has entirely missing(means wat as criticsm of robbin definition
Herieth
what is demand?
Cabdulahi

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Source:  OpenStax, Microeconomics. OpenStax CNX. Aug 03, 2014 Download for free at http://legacy.cnx.org/content/col11627/1.10
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