NO.PZ2022071403000081
问题如下:
Question
In a hypothetical economy, consumption is 70% of pre-tax income, and the average tax rate is 25% of total income. If planned government expenditures are expected to increase by $1.25 billion, the increase in total income and spending, in billions, is closest to:
选项:
A.$2.6. B.$4.2. C.$1.3.解释:
Solution
B is correct.The fiscal multiplier is where
c = marginal propensity to consume = consumption/disposable income
T = the tax rate
Assuming pre-tax income of $100
Disposable income: $100 × (1 – 0.25) = $75
Marginal propensity to consume: $70/$75 = 0.933
The fiscal multiplier: 1/[1 – 0.933(1 – 0.25)] = 3.33
With government expenditure of $1.25 billion, total incomes and spending will rise by $1.25 billion × 3.33 = $4.2 billion
A is incorrect. It calculates the MPC from pre-tax income (MPC = 0.70) but applies the formula correctly: 1/[1 – c(1 – T)]: 1/[1 – 0.70(1 – 0.25)] = 2.10; resulting in an overall stimulus effect of 2.10 × 1.25 = 2.60.
C is incorrect. It uses G/MPC: 1.25/0.933 = 1.34
中文解析
依据公式:
假设税前收入是100美元
可支配收入:100美元×(1 - 0.25) = 75美元
边际消费倾向:$70/$75 = 0.933
财政乘数:1/[1 - 0.933(1 - 0.25)]= 3.33
在政府支出12.5亿美元的情况下,总收入和支出总额将增加12.5亿美元× 3.33 = 42亿美元
A不正确。它从税前收入计算MPC (MPC = 0.70),但正确地应用了公式:1/[1 - c(1 - T)]: 1/[1 - 0.70(1 - 0.25)] = 2.10;总体刺激效应为2.10 × 1.25 = 2.60。
C选项不正确。它使用G/MPC: 1.25/0.933 = 1.34
请问本题mpc的计算为何用税前消费70除以税后收入75?它不应该是税后收入的消费占比吗?跟税前消费有何关联?这步计算不理解