Understanding Economic Concepts and Formulas

This question asks us to match key macroeconomic concepts from List-I with their corresponding formulas or related expressions from List-II. Understanding these concepts is fundamental to analyzing national income determination.

Let's analyze the provided correct matching and explain each pair:

Analyzing the Matched Pairs

• (A) Marginal Propensity to Save (MPS):
  • The Marginal Propensity to Save (MPS) measures the change in saving (\(\Delta S\)) induced by a change in income (\(\Delta Y\)). Its standard formula is \(\Delta S / \Delta Y\). Also, we know that MPC + MPS = 1, so MPS = 1 - MPC.
  • The provided matching links (A) to (III) \(1 – APS\). Average Propensity to Save (APS) is the ratio of total saving to total income (\(S/Y\)). We know that APC + APS = 1, which means APC = 1 - APS. So, (III) represents APC, not MPS. However, based on the given options, this is the specified match.
• (B) Average Propensity to Consume (APC):
  • The Average Propensity to Consume (APC) is the ratio of total consumption (\(C\)) to total income (\(Y\)). Its standard formula is \(C/Y\). It is also related to APS by APC + APS = 1, meaning APC = 1 - APS.
  • The provided matching links (B) to (II) \(\Delta S / \Delta Y\). This expression represents the Marginal Propensity to Save (MPS), not APC. However, based on the given options, this is the specified match.
• (C) Value of Investment Multiplier:
  • The Investment Multiplier (k) shows how much total income changes for a given change in investment. Its standard formula is \(k = \Delta Y / \Delta I\). It is also related to MPC and MPS by \(k = 1 / (1 - MPC) = 1 / MPS\).
  • The provided matching links (C) to (I) \(\Delta Y\). While \(\Delta Y\) is part of the multiplier formula (\(k = \Delta Y / \Delta I\)), \(\Delta Y\) itself is not the value of the multiplier unless the change in investment (\(\Delta I\)) is equal to 1. In the context of matching, \(\Delta Y\) might represent the change in income that results from the multiplier process, implying a unit change in investment.
• (D) Marginal Propensity to Consume (MPC):
  • The Marginal Propensity to Consume (MPC) measures the change in consumption (\(\Delta C\)) induced by a change in income (\(\Delta Y\)). Its standard formula is \(\Delta C / \Delta Y\). Also, MPC + MPS = 1, so MPC = 1 - MPS.
  • The provided matching links (D) to (IV) \(\Delta C / \Delta Y\). This is the standard and correct formula for the Marginal Propensity to Consume (MPC).

Summary of the Matched Pairs (based on the provided correct option)

Based on the matching given in the correct option, the pairs are:

• (A) Marginal Propensity to Save \(\rightarrow\) (III) \(1 – APS\)
• (B) Average Propensity to Consume \(\rightarrow\) (II) \(\Delta S / \Delta Y\)
• (C) Value of Investment Multiplier \(\rightarrow\) (I) \(\Delta Y\)
• (D) Marginal Propensity to Consume \(\rightarrow\) (IV) \(\Delta C / \Delta Y\)

Revision Table: Key Economic Propensities and Multiplier

Additional Information: Understanding Propensities and the Multiplier

The concepts of propensities to consume and save are crucial in Keynesian economics. They help explain how changes in income affect consumption and saving behavior. The marginal propensities (MPC and MPS) are typically used to analyze the effect of a change in income, while average propensities (APC and APS) describe the relationship between total consumption/saving and total income at a particular income level.

• MPC and MPS Relationship: Since any change in income (\(\Delta Y\)) is either consumed (\(\Delta C\)) or saved (\(\Delta S\)), we have \(\Delta Y = \Delta C + \Delta S\). Dividing by \(\Delta Y\) gives \(1 = \Delta C/\Delta Y + \Delta S/\Delta Y\), which is \(1 = MPC + MPS\).
• APC and APS Relationship: Similarly, for total income (\(Y\)), \(Y = C + S\). Dividing by \(Y\) gives \(1 = C/Y + S/Y\), which is \(1 = APC + APS\).
• The Investment Multiplier: The multiplier effect arises because an initial change in investment leads to a change in income, which in turn leads to changes in consumption and saving in subsequent rounds. The size of the multiplier depends on the MPC (or MPS). A higher MPC means a larger proportion of the new income is consumed, leading to a larger increase in demand and income in subsequent rounds, thus a larger multiplier.

These concepts are foundational for understanding macroeconomic models of income determination and the impact of government policies like fiscal policy.