Consumption, Saving and Investment: Keynesian Concepts and Determinants Questions

Question 1

Define consumption.

Accepted Answer

Consumption is expenditure by households on goods and services for satisfying wants.

Question 2

Define saving.

Accepted Answer

Saving is the part of income not spent on consumption; in a simple model S = Y − C.

Question 3

Define investment (macro).

Accepted Answer

Investment is expenditure on capital goods and inventories that increases productive capacity (capital formation).

Question 4

What is MPC?

Accepted Answer

MPC (marginal propensity to consume) is the change in consumption divided by the change in income (ΔC/ΔY).

Question 5

What is APC?

Accepted Answer

APC (average propensity to consume) is the ratio of consumption to income (C/Y).

Question 6

State the relation between MPC and MPS.

Accepted Answer

In a simple model, MPC + MPS = 1.

Question 7

Write any three determinants of consumption.

Accepted Answer

Determinants of consumption include:

1) Level of income and expected future income.
2) Wealth and availability of credit.
3) Price level/inflation expectations and interest rate.

(Any three determinants can be written.)

Question 8

Write any three determinants of saving.

Accepted Answer

Determinants of saving include:

1) Level of income (higher income generally increases saving).
2) Interest rate and availability of financial instruments.
3) Precautionary motive and uncertainty about future.

(Any three determinants can be written.)

Question 9

Write any three determinants of investment.

Accepted Answer

Determinants of investment include:

1) Interest rate (cost of borrowing).
2) Expected profitability and business expectations.
3) Technology and government policy incentives (tax/subsidy).

(Any three determinants can be written.)

Question 10

Differentiate APC and MPC (any three points).

Accepted Answer

APC and MPC differ as follows:

| Point | APC | MPC |
|---|---|---|
| Meaning | average share of income consumed | extra consumption from extra income |
| Formula | C/Y | ΔC/ΔY |
| Use | shows overall pattern at a level of income | shows behavioral response to income change |

(Any three points can be written.)

Question 11

Explain Keynesian consumption function (any three points).

Accepted Answer

Keynesian consumption function states:

1) Consumption depends mainly on current income.
2) C = a + bY, where a is autonomous consumption and b is MPC.
3) Since 0 < b < 1, consumption rises with income but less than proportionately.

(Any three points can be written.)

Question 12

Explain the relation between MPC and multiplier (any three points).

Accepted Answer

Relation between MPC and multiplier:

1) Simple multiplier k = 1/(1 − MPC).
2) Higher MPC means more re-spending, so multiplier is larger.
3) Lower MPC means more saving, so multiplier effect is smaller.

(Any three points can be written.)

Question 13

Explain consumption function and propensities (APC, MPC) with a suitable table.

Accepted Answer

Keynes explained that consumption is closely related to income. The **consumption function** shows the relationship between consumption (C) and income (Y). In its simple form it is written as:

C = a + bY

where **a** is autonomous consumption (minimum consumption even when income is zero) and **b** is the marginal propensity to consume (MPC), with 0 < b < 1.

Two important measures of consumption behavior are APC and MPC:

| Concept | Meaning | Formula |
|---|---|---|
| APC | average share of income consumed | APC = C / Y |
| MPC | extra consumption from extra income | MPC = ΔC / ΔY |

APC tells us what fraction of income is consumed at a particular income level, while MPC tells us how much consumption changes when income changes. Generally, as income rises, MPC is positive and less than 1, so consumption increases but not as fast as income.

Thus, the consumption function and propensities help in understanding aggregate demand and predicting how income changes affect consumption in the economy.

Question 14

Explain saving and its relationship with consumption. Use a table and key relations.

Accepted Answer

Saving is the part of income that is not used for consumption. In a simple macro model (ignoring taxes), the basic relation is:

S = Y − C

This means that for a given income, if consumption increases, saving decreases, and vice versa. Consumption and saving are therefore two complementary uses of income.

| Item | Symbol | Relation |
|---|---|---|
| Income | Y | total income |
| Consumption | C | spending on goods/services |
| Saving | S | S = Y − C |

Similarly, marginal propensities show how changes in income are divided:

- MPC = ΔC/ΔY
- MPS = ΔS/ΔY
- **MPC + MPS = 1**

This relationship is important because it shows that any additional income is either consumed or saved. If MPC is high, people spend more of additional income, raising demand. If MPS is high, saving rises and the immediate demand effect is smaller.

Thus, saving is directly linked to consumption and plays a key role in determining overall demand, investment funds and economic growth.

Question 15

Describe investment and explain multiplier effect with a flowchart and formula.

Accepted Answer

Investment in macroeconomics refers to expenditure on capital goods and inventories that increases future productive capacity. It includes spending on machines, buildings and stock changes. Investment is important because it directly increases aggregate demand and can create multiple rounds of income generation.

When investment increases, firms receive higher demand, produce more and hire more workers. The income paid to workers and suppliers becomes new income, part of which is spent on consumption. This creates further demand and income, continuing in rounds. This is called the **multiplier effect**.

```mermaid
flowchart LR
  A[Increase in investment (ΔI)] --> B[Increase in income (ΔY)]
  B --> C[Increase in consumption (ΔC = MPC×ΔY)]
  C --> D[Further increase in output and income]
  D --> B
```

The simple multiplier is:

k = 1 / (1 − MPC)

So, if MPC is higher, the multiplier is larger because more of additional income is spent and re-spent. If MPC is lower, more income is saved and the multiplier effect becomes smaller.

Thus, investment and the multiplier explain how changes in spending can cause a larger change in national income and employment.

Consumption, Saving and Investment: Keynesian Concepts and Determinants

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