# Determination of Income and Employment Notes | SwaVid

Determination of Income and Employment, NCERT Class 12 Economics: notes with key ideas, definitions, common mistakes and 3 quick checks with worked answers.

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# Determination of Income and Employment

## Definitions, formats and formulas

## Key ideas

## Common mistakes

## Quick checks

## Keep going

## Questions parents ask

## Class 12 Economics on SwaVid

### Ex-ante and ex-post variables

### Consumption and saving functions

### Aggregate demand and aggregate supply

### Short-run equilibrium output

### The investment multiplier

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Notes written by SwaVid from the NCERT textbook.

Class 12 Economics, Chapter 4. Key ideas, definitions and common mistakes.

CBSE does not print marks for a single chapter.

Short answer. This chapter explains how aggregate demand and aggregate supply determine equilibrium output, income, and employment in the short run. It shows how changes in autonomous spending produce magnified changes in total income through the investment multiplier.

Source: NCERT Introductory Macroeconomics (Reprint 2026-27) , Chapter 4, Determination of Income and Employment

Ex-ante variables refer to planned or intended values of consumption, saving, or investment before production takes place. Ex-post variables are the actual realized or measured values at the end of the period.

Consumption depends on income through autonomous consumption and the marginal propensity to consume. Saving is the unspent portion of income, and the marginal propensity to save is the fraction of additional income saved.

Aggregate demand consists of planned consumption and planned autonomous investment in a two-sector economy. Aggregate supply equals total national income produced in the economy.

Equilibrium output occurs where aggregate demand equals aggregate supply, or equivalently, where planned investment equals planned saving. Prices and the capital stock remain constant in this short-run Keynesian framework.

An initial change in autonomous investment causes a larger change in total income through repeated rounds of spending. The size of this multiplier depends directly on the marginal propensity to consume.

Try each question first. Then tap it to see the answer.

Multiplier k = 1 / (1 - MPC) = 1 / (1 - 0.75) = 1 / 0.25 = 4

Change in income ΔY = k × ΔI = 4 × 500 = 2000

₹ 2000 crore

Total autonomous expenditure A bar = c bar + I bar = 100 + 200 = ₹ 300 crore

Equilibrium condition: Y = A bar + c × Y, so Y = 300 + 0.8 × Y

Y × (1 - 0.8) = 300

0.2 × Y = 300, so Y = 300 / 0.2 = 1500

₹ 1500 crore

ΔY = 1500 - 1000 = ₹ 500 crore

ΔS = 350 - 200 = ₹ 150 crore

MPS = ΔS / ΔY = 150 / 500 = 0.3

MPC = 1 - MPS = 1 - 0.3 = 0.7

MPS = 0.3 and MPC = 0.7

Government Budget and the Economy .

National Income Accounting .

Money and Banking .

The 13 chapters of Class 12 Economics .

CBSE does not give marks to one chapter. It prints marks for units or parts, and the chapter list page shows them all.

No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed.

Government Budget and the Economy.

SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works.

- Ch 4 NCERT book
- 80 marks, theory paper
- 3 quick checks
- Using ex-post saving and investment to explain equilibrium . Equilibrium requires ex-ante (planned) saving to equal ex-ante (planned) investment. Ex-post saving and ex-post investment are always equal by accounting identity, even outside equilibrium.
- Confusing MPC with APC in the multiplier formula . Use MPC (the change in consumption per unit change in income) to calculate the multiplier: k = 1 / (1 - MPC). APC is total consumption divided by total income and cannot be substituted into the multiplier formula.
- Assuming equilibrium output must always equal full employment output . Equilibrium income can occur below full employment (underemployment equilibrium) or above it. Full employment is only a special case where aggregate demand fully absorbs the productive capacity.

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