CEVAP:

When the other factors effecting consumption are assumed to be constant, an increase in population will increase consumption expenditures. Here, both the increase in the number of people in the country and the changes in the age composition of the population have an effect on the consumption expenditures. While the size of the population affects the location of the consumption function, the age composition of the population has an effect on the slope of the consumption function. Other factors being constant, an increase in the size of population leads to an increase in autonomous consumption, and therefore the consumption function shifts upward. Considering the age composition of the population, it is known that the young population spends more on durable consumption goods and therefore the young population has a higher marginal propensity to consume than the elderly population. Since the slope of consumption function is measured by MPC, the rising share of the young people in total population will make consumption function steeper.