To determine whether the variables \( x \) (years) and \( y \) (megawatts) have a proportional relationship, we need to check if the ratio \( \frac{y}{x} \) is constant for all pairs of values in the table.
Let's compute the ratio for each pair:
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For \( x = 13 \) and \( y = 312 \): \[ \frac{y}{x} = \frac{312}{13} = 24 \]
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For \( x = 14 \) and \( y = 336 \): \[ \frac{y}{x} = \frac{336}{14} = 24 \]
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For \( x = 18 \) and \( y = 432 \): \[ \frac{y}{x} = \frac{432}{18} = 24 \]
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For \( x = 35 \) and \( y = 840 \): \[ \frac{y}{x} = \frac{840}{35} = 24 \]
Since the ratio \( \frac{y}{x} \) is consistently 24 for all the pairs, \( x \) and \( y \) have a proportional relationship.
Therefore, the answer is yes.