5
QuizMultiple Choice

Proportional Relationships

Question 5 • WI-Mathematics Grade 8 A

Caleb made the table below to show the number of hours he works and the amounts he earns over a four-week period.Caleb’s EarningsHours12151821Earnings(in dollars)140170200230Which describes whether the relationship between the earnings and the number of hours represents a direct variation?

Answer
H
He earns 20 more than 10 times the number of hours he works each week, so the earnings vary directly with the hours.
T
The earnings increase by 30 for every increase of 3 hours, so the earnings vary directly with the hours.
T
The ratios of earnings to hours are not the same each week, so the earnings do not vary directly with the hours.
T
The earnings increase at a steady rate, so the earnings do not vary directly with the hours.

Explanation

For direct variation, earnings must equal a constant times hours, so the ratio of earnings to hours must be the same each week. Here, 140 ÷ 12 is about 11.67, while 170 ÷ 15 is about 11.33, so the ratios are not equal. The earnings follow a steady increase, but that alone does not make the relationship a direct variation.

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