Utility
Đã giới thiệu| English | Ý nghĩa |
|---|---|
| diminishing marginal utility/dɪˈmɪnɪʃɪŋ ˈmɑːdʒɪnl juːˈtɪlɪti/ | tính边际效用 diminishing marginal utility |
| marginal utility/ˈmɑːdʒɪnl juːˈtɪlɪti/ | tính边际效用 marginal utility |
| utility/juːˈtɪlɪti/ | lợi ích |
| total utility/ˈtəʊtl juːˈtɪlɪti/ | tổng lợi ích |
| equi-marginal principle/ˈekwi ˈmɑːdʒɪnl ˈprɪnsɪpl/ | nguyên tắc cân bằng边际效用 |
Why the second ice cream is never as good
- The first ice cream on a hot day is bliss; the second is nice; the fourth makes you queasy. Each extra one adds less satisfaction.
- That pattern — diminishing marginal utility 边际效用递减 — quietly explains the downward-sloping demand curve.
Diminishing marginal utility lab
total utility rises more slowly as quantity increases
Add units consumed and see why extra satisfaction usually falls.
Total and marginal utility 边际效用
- Utility 效用 is the satisfaction from consuming a good.
- Total utility 总效用 (TU) is the overall satisfaction; marginal utility (MU) is the extra utility from one more unit.
- $MU$ = the change in $TU$ from the next unit.
Worked example. If total utility from 2, 3 ice creams is 18 then 24, the marginal utility of the third is 24 − 18 = 6.
Total utility rises while marginal utility falls
Total utility from 2 then 3 ice creams is 18 then 24. What is the marginal utility of the 3rd?
Độ khó 2/5 · 140 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
MU = change in TU = 24 − 18 = 6.
Marginal utility is the change in ______ utility from one more unit.
Độ khó 1/5 · 100 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
MU = ΔTU.
Diminishing marginal utility
- As you consume more, each extra unit adds less — MU falls.
- That's why you'll only buy more at a lower price — the root of the downward demand curve.
Consumers spend limited income to get the most utility (satisfaction)
Diminishing marginal utility means each extra unit consumed gives:
Độ khó 1/5 · 100 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
MU falls as consumption rises — the basis of the downward demand curve.
Diminishing marginal utility helps explain why the demand curve slopes:
Độ khó 1/5 · 100 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
Since extra units are worth less, buyers will only take more at a lower price.
The equi-marginal principle 等边际原则
- To maximise utility on a budget, spend so the utility per dollar is equal across goods:
- If one good gives more utility per dollar, switch spending to it until they balance.
Utility is maximised when the marginal utility per dollar is equal across all goods.
Độ khó 1/5 · 100 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
MU_A/P_A = MU_B/P_B — otherwise you could gain by switching spending.
You've got it
- utility = satisfaction; MU = extra utility from one more unit (= ΔTU)
- diminishing marginal utility: each extra unit adds less → downward demand
- maximise with $\dfrac{MU_A}{P_A} = \dfrac{MU_B}{P_B}$ (equal utility per dollar)
Write from a marginal utility of 4
- Total utility is 30 at 4 ice creams.
- Total utility is 34 at 5 ice creams.
What is the marginal utility of the 5th ice cream?
Marginal utility is the change in total utility.
What is the marginal utility of the 5th ice cream?
Độ khó 1/5 · 100 xu + một phần thưởng nhỏ cho lần hoàn thành đầu tiên trong ngày
34 minus 30 is the extra satisfaction. Other options — 6 (the lesson's 3rd ice cream); 34 (the new total utility).