To determine if the given sets of ratios are proportions, we can check if the cross products of the fractions are equal. A proportion states that \( \frac{a}{b} = \frac{c}{d} \) if and only if \( a \cdot d = b \cdot c \).
Let's evaluate each option:
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For \( \frac{2.25}{12} = \frac{90}{40} \):
- Cross products: \( 2.25 \times 40 \) and \( 12 \times 90 \)
- \( 2.25 \times 40 = 90 \) (since \( 2.25 \times 40 = 90 \))
- \( 12 \times 90 = 1080 \)
- Since \( 90 \neq 1080 \), this is not a proportion.
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For \( \frac{2.5}{10} = \frac{90}{40} \):
- Cross products: \( 2.5 \times 40 \) and \( 10 \times 90 \)
- \( 2.5 \times 40 = 100 \)
- \( 10 \times 90 = 900 \)
- Since \( 100 \neq 900 \), this is not a proportion.
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For \( \frac{2.25}{10} = \frac{90}{40} \):
- Cross products: \( 2.25 \times 40 \) and \( 10 \times 90 \)
- \( 2.25 \times 40 = 90 \) (since \( 2.25 \times 40 = 90 \))
- \( 10 \times 90 = 900 \)
- Since \( 90 \neq 900 \), this is not a proportion.
Since none of the sets of ratios are equal based on their cross products, we conclude that:
None of these sets of ratios is a proportion.