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Exercises · Q5

Q.Measure the level of ex-ante aggregate demand when autonomous investment and consumption expenditure (AA) is Rs 50 crores, and MPS is 0.20.2 and level of income (YY) is Rs 4000 crores. State whether the economy is in equilibrium or not (cite reasons).

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Ex-ante aggregate demand is the planned total spending in the economy. Using the formula AD=Aˉ+cYAD = \bar{A} + cY, with Aˉ=50\bar{A}=50, MPS =0.2=0.2 (so MPC =0.8=0.8), and Y=4000Y=4000, we get AD=50+0.8×4000=3250AD = 50 + 0.8 \times 4000 = 3250 crores. Since AD<YAD < Y, the economy is not in equilibrium — there is excess supply, leading to unplanned inventory accumulation.

The core idea here is the equilibrium condition in the Keynesian simple model: equilibrium national income occurs where ex-ante aggregate demand (planned spending) equals ex-ante aggregate supply (planned output, which is the same as income YY).

Ex-ante aggregate demand (ADAD) is the total planned expenditure in the economy. In a two-sector model (households and firms), it has two components:

  • Autonomous expenditure (Aˉ\bar{A}): spending that does not depend on income — includes autonomous consumption and investment. Given as Rs 50 crores.
  • Induced consumption: spending that depends on income, given by cYcY, where cc is the marginal propensity to consume (MPC).

We are given the marginal propensity to save (MPS) as 0.20.2. Since households either consume or save out of additional income,

MPC+MPS=1MPC + MPS = 1

So,

c=1−MPS=1−0.2=0.8c = 1 - MPS = 1 - 0.2 = 0.8

AD=Aˉ+cYAD = \bar{A} + cY

Now substitute the given values:

AD=50+0.8×4000AD = 50 + 0.8 \times 4000

AD=50+3200AD = 50 + 3200

AD=3250 croresAD = 3250 \text{ crores}

The ex-ante aggregate demand is Rs 3250 crores.


Is the economy in equilibrium?

Equilibrium requires AD=YAD = Y. Here,

AD=3250andY=4000AD = 3250 \quad \text{and} \quad Y = 4000

Since AD<YAD < Y, planned spending is less than the output produced.

What happens in such a situation? Firms find that they are selling less than they produced. The unsold goods pile up as unplanned inventory accumulation. This is a signal that production is too high relative to demand. Firms will respond by cutting output in the next period, moving the economy toward a lower equilibrium income. …

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