Can MPS or MPC ever be negative?

Answer :

No, neither MPS or MPC can ever be negative. Because MPS is the ratio between additional saving (∆S ) and additional income(∆Y). Likewise, MPC is the ratio between additional consumption (∆C) and additional income (∆Y). The ratio ∆S / ∆Y refers to slope of Saving function which is always positive because of positive relationship between S and Y. Likewise, the ratio ∆C / ∆Y refers to slope of consumption function which is always positive because of positive relationship between C and Y.

Also read :

Consumptionfunction

Savingfunction

Explain that sum total of MPC and MPS equal to 1 ?

Answer : 

We know that:

MPS = ∆S / ∆Y

MPC = ∆C / ∆Y

We also know that:

(Additional income is either used in increasing consumption or saving)

∆Y = ∆C +∆ S

(Dividing both sides of the equation by ∆Y)

∆Y / ∆Y = ∆C / ∆Y + ∆S / ∆Y

1 = MPC + MPS

So that,

MPC + MPS = 1

Or, MPC = 1 – MPS

Or, MPS = 1 – MPC

MPC is generally less than unity and greater than zero. It means that a part of increase in income is consumed and the other part is saved.

So, the aggregate MPC and MPS must be equal to unity. Thus, if half of the increase in income is spent on consumption, the other half must be saved.

So that when MPC = 1/ 2 (half), then MPS = 1/ 2(half) also implying that

MPC + MPS = 1 always.

Explain that sum total of APC and APS equal to 1 ?

Answer :

We know that:

APC = C / Y

APS = S / Y

We also know that:

Y = C + S (income is either consumed or saved)

(Dividing both sides of the equation by Y)

Y / Y = C / Y + S / Y

1 = APC + APS

So that,

APC + APS = 1

Or, APC = 1 – APS

Or, APS = 1 – APC

Give the equation for a linear consumption function?

Answer:

The general equation for a linear consumption function is expressed as:

C = a + cY

Where,

C : is the aggregate consumption expenditure

a : represent a positive constant equal to the level of consumption at zero level of income or autonomous consumption.

c : denotes marginal propensity to consume or the slope of the consumption line

Y : Income
Explain consumption function in tabular and graphical form? To know about this read  

Tabularexplanation of Consumption function

Graphical Explaination of the Consumption function

In APC and MPC the value of which parameter can be greater than one and when?

Answer : 

Value of APC can be greater than one. It happens when the level of income is low and C >Y.

Value of MPC cannot be greater than one. MPC is the ratio between additional consumption and additional income (∆C / ∆Y). Since additional consumption is only part of additional income, and after certain level of income is reached, people start saving a part of income.

Since increase in consumption (∆C) is less than that of increase in income (∆Y) the value of MPC must be less than one or cannot be greater than one.