Solution: The ratio of change in consumption (XC) due to change in income (XY) is called marginal propensity to consume.
• MPC is that part of additional income which is spent on additional consumption.
• In other words, it measures the ratio of change in consumption expenditure as a result of change in income.
• MPC is always greater than zero (MPC > 0) but less than 1 (MPC < 1).
• The reason is that incremental income can be either consumed or entirely saved.