A proportional relationship means that the ratio of \( y \) to \( x \) remains constant across all values.
Let's check each option:
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First Table: \[ \begin{align*} x & : y \ 4 & : 2 \quad (y/x = 2/4 = 0.5) \ 9 & : 3 \quad (y/x = 3/9 = 0.333...) \ 16 & : 4 \quad (y/x = 4/16 = 0.25) \end{align*} \] The ratios are not constant.
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Second Table: \[ \begin{align*} x & : y \ 8 & : 2 \quad (y/x = 2/8 = 0.25) \ 12 & : 3 \quad (y/x = 3/12 = 0.25) \ 40 & : 4 \quad (y/x = 4/40 = 0.1) \end{align*} \] The ratios are not constant.
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Third Table: \[ \begin{align*} x & : y \ 2 & : 10 \quad (y/x = 10/2 = 5) \ 5 & : 20 \quad (y/x = 20/5 = 4) \ 6 & : 30 \quad (y/x = 30/6 = 5) \end{align*} \] The ratios are not consistent.
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Fourth Table: \[ \begin{align*} x & : y \ 10 & : 2 \quad (y/x = 2/10 = 0.2) \ 15 & : 3 \quad (y/x = 3/15 = 0.2) \ 40 & : 8 \quad (y/x = 8/40 = 0.2) \end{align*} \] The ratios are consistent at 0.2.
Thus, the fourth table demonstrates a proportional relationship.