Final answer:
The tax multiplier for a nation with a marginal propensity to consume of 0.9 is -9, indicating a decrease in aggregate demand by nine units for each unit increase in taxes.
Step-by-step explanation:
The concept in question relates to the tax multiplier, which operates within the field of macroeconomics and fiscal policy. The marginal propensity to consume (MPC) is a crucial variable for calculating the tax multiplier. To find the tax multiplier when the MPC is 0.9, we use the formula tax multiplier = -MPC / (1 - MPC). Substituting the given MPC value into the formula yields:
Tax Multiplier = -0.9 / (1 - 0.9) = -0.9 / 0.1 = -9.
Hence, the tax multiplier for a nation with an MPC of 0.9 is -9. This result suggests that an increase of one unit in taxes would lead to a decrease in aggregate demand by nine units.