Three countries — Pumpland (P), Xiland (X) and Cheeseland (C) — trade among themselves and with the (other countries in) Rest of World (ROW). All trade volumes are given in IC (international currency). The following terminology is used:
• Trade balance = Exports - Imports
• Total trade = Exports + Imports
• Normalized trade balance = Trade balance / Total trade, expressed in percentage terms
The following information is known.
1. The normalized trade balances of P, X and C are 0%, 10%, and -20%, respectively.
2. 40% of exports of X are to P. 22% of imports of P are from X.
3. 90% of exports of C are to P; 4% are to ROW.
4. 12% of exports of ROW are to X, 40% are to P.
5. The export volumes of P, in IC, to X and C are 600 and 1200, respectively. P is the only country that exports to C.
How much is exported from ROW to ROW, in IC?
Correct Answer :
1008
Solution :
The correct answer is 1008.
To determine the export volume from the Rest of the World (ROW) to itself, we analyze the trade relations between Pumpland (P), Xiland (X), Cheeseland (C), and ROW. Let us define the variables for each country/entity:
Let EP, EX, EC, and EROW be the total export volumes of P, X, C, and ROW, respectively.
Let IP, IX, IC, and IROW be the total import volumes of P, X, C, and ROW, respectively.
Step 1: Relate total exports and total imports using normalized trade balances
The normalized trade balance is defined as:
For Pumpland (P), the normalized trade balance is 0%:
For Xiland (X), the normalized trade balance is 10%:
For Cheeseland (C), the normalized trade balance is -20%:
Step 2: Determine trade details for Cheeseland (C)
We are given that P is the only country that exports to C. Thus, all of C's imports come from P:
Using our relation for Cheeseland's trade:
Now we calculate C's exports to other regions using the given percentages:
• Exports of C to P: 90% of C's exports = 0.90 × 800 = 720
• Exports of C to ROW: 4% of C's exports = 0.04 × 800 = 32
• Exports of C to X: The remaining 6% of C's exports (since C only trades with P, X, and ROW) = 0.06 × 800 = 48
Step 3: Analyze Pumpland's imports and exports to relate EX and EP
From Point 2, 40% of the exports of X are to P:
Also from Point 2, 22% of the imports of P are from X:
Since the imports of P from X must equal the exports of X to P:
Since EP = IP, we also have:
Step 4: Formulate the system of equations for EX and EROW
First, let's look at the total imports of Pumpland (P). P imports from X, C, and ROW:
We know:
• Imports from X = 0.40 EX
• Imports from C = 720
• Imports from ROW = 40% of ROW exports = 0.40 EROW
Thus:
Substitute IP = :
Subtracting 0.40 EX (which is 2/5 EX) from both sides:
Next, let's write the equation for the total imports of Xiland (X). X imports from P, C, and ROW:
• Imports from P = 600
• Imports from C = 48
• Imports from ROW = 12% of ROW exports = 0.12 EROW
Thus:
Since , we have:
Step 5: Solve the system of equations
From Equation 2, express EX in terms of EROW:
Substitute this into Equation 1:
Expanding:
Step 6: Compute exports from ROW to ROW
The total exports of ROW are distributed as follows:
• Exports to P: 40% of EROW
• Exports to X: 12% of EROW
• Exports to C: 0% (since Pumpland is the only country exporting to C)
• Exports to ROW (itself): The remaining portion, which is:
Therefore, the volume exported from ROW to ROW is:
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