Question

Difficulty: MediumCircular Flow of Income

In an open four-sector economy, the circular flow of income is in equilibrium when total leakages (withdrawals) equal total injections. If planned savings (SS) is $80 million\$80\text{ million}, imports (MM) are $45 million\$45\text{ million}, planned investment (II) is $95 million\$95\text{ million}, government expenditure (GG) is $60 million\$60\text{ million}, and exports (XX) are $40 million\$40\text{ million}, what is the required value of government tax revenue (TT) in millions of dollars?

Answer: 70 million dollars

Answer

The required government tax revenue to achieve circular flow equilibrium is 70 million dollars.
Circular flow equilibrium in a four-sector economy occurs when total leakages (withdrawals) equal total injections: S+T+M=I+G+XS + T + M = I + G + X. Summing total injections gives $95+$60+$40=$195 million\$95 + \$60 + \$40 = \$195\text{ million}. Substituting known leakages gives $80+T+$45=$125+T\$80 + T + \$45 = \$125 + T. Equating total leakages to total injections yields $125+T=$195\$125 + T = \$195, which solves to T=70 million dollarsT = 70\text{ million dollars}.

Step-by-Step Solution

1
Identify the equilibrium condition for a four-sector circular flow model
S+T+M=I+G+XS + T + M = I + G + X
Macroeconomic equilibrium in a four-sector economy requires total withdrawals (savings, taxation, imports) to equal total injections (investment, government spending, exports).
2
Compute total injections into the income stream
I+G+X=95+60+40=195 million dollarsI + G + X = 95 + 60 + 40 = 195\text{ million dollars}
Summing investment spending, government purchases, and export earnings provides the total injection.
3
Substitute known values into the leakages-injections identity
80+T+45=195    125+T=19580 + T + 45 = 195 \implies 125 + T = 195
Combining known leakages (savings and imports) with the unknown tax revenue variable.
4
Solve for tax revenue (TT)
T=195125=70 million dollarsT = 195 - 125 = 70\text{ million dollars}
Subtracting non-tax withdrawals from total injections yields the required tax value.

Key Concept

Four-Sector Circular Flow Equilibrium (Total Leakages = Total Injections)
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