To determine which two ratios form a proportion, we need to check if the cross-products are equal. A proportion is formed when two ratios, \( \frac{a}{b} \) and \( \frac{c}{d} \), satisfy the condition \( a \cdot d = b \cdot c \).
Let's evaluate the provided pairs:
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4/20 and 2/5
- Cross-products: \( 4 \cdot 5 = 20 \) and \( 20 \cdot 2 = 40 \) → Not equal, so not a proportion.
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20/4 and 2/5
- Cross-products: \( 20 \cdot 5 = 100 \) and \( 4 \cdot 2 = 8 \) → Not equal, so not a proportion.
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4/20 and 1/5
- Cross-products: \( 4 \cdot 5 = 20 \) and \( 20 \cdot 1 = 20 \) → Equal, so they form a proportion.
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20/4 and 1/5
- Cross-products: \( 20 \cdot 5 = 100 \) and \( 4 \cdot 1 = 4 \) → Not equal, so not a proportion.
The correct answer is 4/20 and 1/5. These two ratios form a proportion.
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