Ratios and Proportional Relationships Flashcards

A store marks up items by 25%. If an item costs $48 wholesale, what is the selling price?

Answer: $60

A 25% markup on $48 is $48 × 0.25 = $12; the selling price is $48 + $12 = $60.

The equation y = 7x represents a proportional relationship. Which ordered pair lies on this line?

Answer: (3, 21)

When x = 3, y = 7 × 3 = 21, so (3, 21) satisfies the equation y = 7x.

Two quantities x and y are proportional. The table shows: x = 5, y = 15; x = 10, y = 30. What is the value of y when x = 8?

Answer: 24

The constant of proportionality is k = 15/5 = 3, so y = 3 × 8 = 24.

A 6th grader runs 1.5 miles in 18 minutes. At this rate, how long will it take to run 4 miles?

Answer: 48 minutes

The unit rate is 18/1.5 = 12 minutes per mile; 4 miles × 12 min/mile = 48 minutes.

Which of the following describes a non-proportional linear relationship?

Answer: y = 2x + 4

y = 2x + 4 has a y-intercept of 4 (not zero), so it does not pass through the origin and is not proportional.

If 15% of a number is 45, what is the number?

Answer: 300

Set up the equation 0.15 × n = 45; divide both sides by 0.15 to get n = 300.

A swimming pool holds 12,000 gallons. It is being filled at a rate of 400 gallons per hour. Which equation represents the number of gallons g after h hours?

Answer: g = 400h

Since the pool starts empty and is being filled at 400 gallons per hour, g = 400h is the proportional relationship.