Explain the following:
Marginal propensity to consume (MPC). 

Marginal propensity to consume (MPC). MPC is ratio of change in consumption (ΔC) due to change in incotnp (ΔY), Literally marginal means additional (or incremental) and propensity to consume means desire (or urge) to consume. Thus MPC is the ratio of additional consumption (ΔC) to additional income (ΔY). It indicates the proportion of additional income that is being spent on additional consumption. MPC is calculated by dividing the increment (or decrement) in consumption with the corresponding increment (or decrement) in income. Symbolically;
MPC = ΔC/ΔY
where A (called delta) indicates 'change in'. For instance, if income of a country increases from  र 5,000 crores to र 5,500 crores (i.e., by र 500 crores) and as a result, consumption expenditure goes up from र 4,000 crores to 4,300 crores (i.e., by र 300 crores), then
 It means MPC is 0.6. This shows a rupee change in income causes a 0.60 rupee (i.e. 60 paise) change in consumption.

Features of MPC:
(i) MPC is always greater than zero (MPC > 0) but less than 1 (MPC < 1). Thus value of MPC always lies between 0 and 1. Its reason is that incremental income can be either consumed or entirely saved. If entire incremental income is consumed, then change in consumption (ΔC) will be equal to change in income (ΔY) making MPC = 1. In case entire income is saved, then change in consumption is zero making MPC = 0.
(ii) MPC falls with increase in income. As a person becomes richer, he tends to consume a smaller portion of increase in income.
(iii) MPC is assumed to be constant for a straight line consumption curve.
(iv) MPC, i.e., ΔC/ΔY is graphically the slope of consumption curve.