Determination of Income & Employment NCERT Solutions Class 12 PDF 2026

Ans:
Marginal Propensity to Consume (MPC): It is the ratio of change in consumption (ΔC) to the change in income (ΔY). It indicates the proportion of additional income that is spent on consumption. MPC = ΔC / ΔY.
Relationship with MPS: Since any additional income can only be either consumed or saved, the sum of marginal propensity to consume and marginal propensity to save is always equal to 1.
Formula: MPC + MPS = 1. Therefore, MPS = 1 - MPC.

Ans:
Ex-ante Investment: It refers to the planned or desired investment that firms intend to make in an economy during a given period. Equilibrium occurs only when ex-ante saving equals ex-ante investment.
Ex-post Investment: It refers to the actual or realized investment made in an economy during a given period. By accounting definition, ex-post saving is always equal to ex-post investment because any unsold goods are treated as unintended inventory investment.

Ans: A parametric shift refers to the change in the position or slope of a line when the parameters (constants) of its equation change. For the consumption curve C = c̅ + bY:
(i) When slope (b or MPC) decreases: The curve becomes flatter. It rotates downwards around the intercept on the Y-axis.
(ii) When intercept (c̅ or autonomous consumption) increases: The entire curve shifts parallelly upwards. The slope remains the same, but it starts from a higher point on the Y-axis.

Ans: The Investment Multiplier (k) expresses the relationship between an initial increase in investment and the resulting multiple increase in national income.
Formula: k = ΔY / ΔI or k = 1 / (1 - MPC).
Working: When an initial investment of ₹100 crores is made (say, building a bridge), it generates ₹100 crores of income for workers and suppliers. If the MPC is 0.8, these people will spend ₹80 crores (0.8 × 100) on consumption. This ₹80 crores becomes income for others, who will then spend ₹64 crores (0.8 × 80). This chain continues infinitely. The total increase in income will be: ΔY = 100 × (1 / 0.2) = ₹500 crores.

Ans: Autonomous consumption (c̅) refers to the minimum level of consumption that takes place even when the income level is zero. People survive by either drawing from past savings (dissaving) or borrowing.

Ans: Full employment refers to a situation in which all those people who are willing and able to work at the existing wage rate get work. No, it does not mean zero unemployment; there is always some natural 'frictional' or 'structural' unemployment present in the economy.

Ans: Involuntary unemployment occurs when people are able to work and are willing to work at the prevailing wage rate, but fail to get employment. This is the type of unemployment Keynesian economics aims to solve.

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

Ans: In a simple two-sector economy, Aggregate Demand (AD) consists of two components:
1. Private Final Consumption Expenditure (C) by households.
2. Private Investment Expenditure (I) by firms.

Ans: Deficient demand occurs when Aggregate Demand (AD) is less than Aggregate Supply (AS) at the full employment level. The gap between the required full employment AD and the actual AD is called the Deflationary Gap. It leads to involuntary unemployment, falling prices, and unwanted inventory accumulation.
Two Fiscal Measures to correct it:
1. Increase Government Spending: The government should heavily invest in public works (roads, bridges) to inject money into the economy, raising aggregate demand.
2. Decrease Taxes: Reducing income taxes will increase the disposable income of households, leading to higher consumption expenditure and an upward shift in AD.

Ans: According to the Saving-Investment (S=I) approach, the equilibrium level of income is established where planned saving equals planned investment.
1. In a two-sector model, Investment (I) is assumed to be autonomous, so it is a horizontal straight line parallel to the X-axis.
2. The Saving curve (S) starts from the negative Y-axis (due to autonomous consumption leading to dissaving at zero income) and slopes upwards.
3. Equilibrium Point (E): The point where the Saving curve intersects the Investment line is the equilibrium. At this point, the leakages from the circular flow (Saving) are exactly balanced by the injections (Investment).
If S > I, inventory piles up, and producers cut output until S falls back to I. If I > S, inventory falls, and producers increase output until equilibrium is restored.

Ans: Excess demand occurs when Aggregate Demand (AD) is greater than Aggregate Supply (AS) at the full employment level. The gap by which actual AD exceeds the full employment AD is called the Inflationary Gap. Since the economy is already at full employment, output cannot be increased. This excess demand purely leads to a rise in the general price level (inflation).
Two Monetary Measures (by Central Bank):
1. Increase Repo Rate / Bank Rate: Makes borrowing expensive for commercial banks, leading to higher interest rates for the public. This discourages taking loans, reducing investment and consumption.
2. Increase CRR/SLR: Banks have to keep more money as reserves, reducing their credit creation capacity. Money supply falls, which pulls Aggregate Demand down.

Ans: Since Income (Y) is either consumed (C) or saved (S), Y = C + S. Therefore, Saving = Y - C.
1. Draw a 45-degree line from the origin representing Income (Y = AS).
2. Draw the consumption curve (C) starting from above the origin on the Y-axis (representing autonomous consumption, c̅).
3. The point where the C curve intersects the 45-degree line is the Break-even point (C = Y). At this point, Saving is zero.
4. Drop a perpendicular line from the break-even point to the X-axis below. This is where the Saving curve intersects the X-axis.
5. Before the break-even point, C > Y, so the Saving curve lies in the negative quadrant (dissaving). It starts from -c̅ on the Y-axis. After the break-even point, Y > C, so the Saving curve is positive and slopes upward.

Ans:
At equilibrium, Y = AD. In a 2-sector model, AD = C + I.
Y = C + I
Y = (100 + 0.5Y) + 200
Y - 0.5Y = 300
0.5Y = 300
(i) Equilibrium Income (Y) = 300 / 0.5 = ₹600 crores.

To find consumption at equilibrium:
C = 100 + 0.5(600)
C = 100 + 300
(ii) Consumption at Equilibrium (C) = ₹400 crores.

Ans: This statement describes the Paradox of Thrift. If an individual saves more, their personal wealth increases, which is good. However, if *everyone* in the economy decides to save more (higher MPS), it means they are consuming less (lower MPC). A fall in consumption drastically reduces Aggregate Demand. Producers will cut down production, leading to massive unemployment and a fall in national income. Ultimately, the total saving in the economy might actually fall or remain unchanged due to lower income. Thus, what is a virtue for an individual becomes a vice for the nation.

Ans: Both Assertion (A) and Reason (R) are True, and (R) is the correct explanation of (A).
APC = C / Y. At very low levels of income, basic survival requires a minimum autonomous consumption. Hence, Consumption (C) exceeds Income (Y), making the numerator larger than the denominator, resulting in an APC > 1. This excess consumption is financed by dissaving.

Ans: No, MPC can never be negative. It always lies between 0 and 1. When income increases, consumption either remains the same (MPC=0) or increases. People do not reduce their absolute consumption when their income rises.

Ans: An increase in the marginal propensity to import means that citizens are spending a larger fraction of their additional income on foreign goods. This acts as a leakage from the domestic circular flow, causing the Aggregate Demand for domestic goods to fall. Consequently, the equilibrium level of national income will decrease.

Ans: Selling government securities in the open market (OMO) absorbs excess liquidity from the commercial banks and the public. When the public buys these bonds, money transfers from the economy to the Central Bank. This reduces the lending capacity of banks and the purchasing power of the public, which brings down Aggregate Demand and controls inflation.