What is Law of Diminishing Marginal Utility?

S7-SA7-0142

Grade Level:

Class 12

AI/ML, Physics, Biotechnology, FinTech, EVs, Space Technology, Climate Science, Blockchain, Medicine, Engineering, Law, Economics

Definition

What is it?

The Law of Diminishing Marginal Utility states that as a person consumes more and more units of a specific good, the additional satisfaction (utility) they get from each extra unit tends to decrease. Simply put, the more you have of something, the less extra happiness each new unit gives you.

Simple Example

Quick Example

Imagine you are very hungry and eat your first dosa. It tastes amazing! Your second dosa is also good, but maybe not as mind-blowing as the first. By the time you eat your third or fourth dosa, you are full, and the extra satisfaction from each new dosa keeps going down. This decreasing satisfaction from each additional dosa is diminishing marginal utility.

Worked Example

Step-by-Step

Let's calculate the marginal utility of eating samosas:

Step 1: You eat 1st samosa. Total satisfaction = 10 units. Marginal utility = 10 units.
---Step 2: You eat 2nd samosa. Total satisfaction = 18 units. Marginal utility = (18 - 10) = 8 units.
---Step 3: You eat 3rd samosa. Total satisfaction = 24 units. Marginal utility = (24 - 18) = 6 units.
---Step 4: You eat 4th samosa. Total satisfaction = 28 units. Marginal utility = (28 - 24) = 4 units.
---Step 5: You eat 5th samosa. Total satisfaction = 30 units. Marginal utility = (30 - 28) = 2 units.
---Answer: As you can see, the marginal utility (additional satisfaction) from each extra samosa decreases from 10 to 8, then 6, 4, and 2 units.

Why It Matters

This law helps businesses understand how much people are willing to pay for goods and services, influencing pricing strategies. It's crucial in FinTech for designing investment products and in Economics to explain consumer behavior and demand. Understanding this can even help you make smarter choices about saving money or buying new gadgets.

Common Mistakes

MISTAKE: Thinking total utility decreases. | CORRECTION: Total utility usually increases, but at a slower and slower rate. It's the *additional* satisfaction (marginal utility) that decreases.

MISTAKE: Believing the law applies to all goods equally, regardless of quantity. | CORRECTION: The law is most noticeable after consuming a certain quantity. For very scarce goods, marginal utility might remain high for longer.

MISTAKE: Confusing marginal utility with average utility. | CORRECTION: Marginal utility is the satisfaction from ONE additional unit. Average utility is total utility divided by the number of units consumed.

Practice Questions

Try It Yourself

QUESTION: If the total utility from 2 gulab jamuns is 25 units and from 3 gulab jamuns is 32 units, what is the marginal utility of the 3rd gulab jamun? | ANSWER: 7 units

QUESTION: A student gets 50 'happiness points' from their first hour of mobile gaming, 40 from the second, and 20 from the third. Is this an example of diminishing marginal utility? Explain. | ANSWER: Yes, because the additional happiness (marginal utility) from each extra hour of gaming is decreasing (50, then 40, then 20).

QUESTION: A person consumes mangoes. The marginal utility of the 1st mango is 15, the 2nd is 12, the 3rd is 8. What is the total utility after consuming 3 mangoes? If the 4th mango gives 0 marginal utility, what does this imply? | ANSWER: Total utility after 3 mangoes = 15 + 12 + 8 = 35 units. If the 4th mango gives 0 marginal utility, it implies the person is completely satisfied or full, and an additional mango would not provide any extra satisfaction.

MCQ

Quick Quiz

Which of the following best describes the Law of Diminishing Marginal Utility?

Total satisfaction decreases with each additional unit consumed.

The additional satisfaction from consuming an extra unit decreases.

The price of a good decreases as more units are consumed.

All goods provide the same level of satisfaction.

The Correct Answer Is:

The Law of Diminishing Marginal Utility specifically talks about the *additional* satisfaction (marginal utility) decreasing, not the total satisfaction. Options A, C, and D are incorrect descriptions of the law.

Real World Connection

In the Real World

This law explains why mobile network providers offer different data packs – the first few GBs are crucial, but additional GBs might be less valuable to you. It also helps companies like Netflix or Spotify understand how many new features to add; initially, new features are exciting, but after a point, adding more might not increase user satisfaction much.

Key Vocabulary

Key Terms

UTILITY: The satisfaction or benefit a consumer gets from consuming a good or service. | MARGINAL UTILITY: The additional satisfaction gained from consuming one more unit of a good or service. | TOTAL UTILITY: The overall satisfaction gained from consuming all units of a good or service. | CONSUMPTION: The act of using goods and services to satisfy needs and wants.

What's Next

What to Learn Next

Next, you should explore the concept of Consumer Equilibrium. This builds on diminishing marginal utility to show how consumers decide what combination of goods to buy to maximize their overall satisfaction given their budget. It's a super important concept in understanding market demand!