Question

If the marginal propensity to consume is .9, then what is the marginal propensity to save?

Answer 1

The complementary proportion.

Explanation:

As macroeconomic basic models assume that one individual either saves his money or spends his money on consumption, marginal propensity to consume (`mpc`) and marginal propensity to save (`mps`) are complementary and sum up `1`.

Mathematically: `mpc+mps=1`

Thus, if `mpc=0.9`, then `mps=0.1`