Direct and Inverse Variations

 Y varies directly with x, and y is 84 when x is 16. Which equation represents this situation?

• y=1344x
• y=100x
• y=5.25x
• y=4/21x

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.3

CCSS.8.F.B.4

The number of hours to paint a house varies inversely with the number of painters working. A 2400-square foot house can be painted in 27 hours by 6 painters. How many painters would need to work in order to paint the house in 18 hours?

• 8 painters
• 10 painters
• 9 painters
• 11 painters

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.2

CCSS.HSA.CED.A.4

The time it takes to fly from Los Angeles to New York varies inversely as the speed of the plane. If the trip takes 6 hours at 900 km/h, how long would it take at 800 km/h?

• 5.33 hours 
• 6.75 hours 
• 12 hours 
• 10 hours 

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.4

CCSS.HSA.SSE.A.1

The gas pressure in a chamber varies directly with the temperature in the chamber. If the pressure in the chamber is 150 atmospheres (atm) when the chamber is at 50 degrees, what is the pressure in the chamber when the temperature of the chamber is 75 degrees? 

• 175 atm
• 200 atm
• 225 atm
• 275 atm

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.2

CCSS.HSA.REI.B.3

CCSS.HSA.SSE.A.1

Which of the following represents direct variation?

• y = kx
• y = k/x
• y = x/k
• y = mx + b

Tags

CCSS.HSF.BF.A.1

Which of the following represents indirect variation?

• y = kx
• y = k/x
• y = x/k
• y = mx + b

The number of kilograms of water in a person’s body varies directly as the person’s mass.  A person with a mass of 90 kg contains 60 kg of water.  How many kilograms of water are in a person whose mass is 75 kg?

• 50 kg water
• 72 kg water
• 94 kg water
• 150 kg water

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.REI.B.3

CCSS.HSA.SSE.A.1

The cost per person to rent a mountain cabin varies inversely to the number of people who share the rent. If the cost is $36 per person when 5 people share, what is the cost per person when 8 people share?

• $22.50

• $57.60

• $4.50

• $12.50

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.4

CCSS.HSA.REI.B.3

CCSS.HSA.SSE.A.1

In a random sampling of 200 cars of a model, 3 have manufacturing defects. If there is a direct variation between the number of cars and the number of defects, how many of 10,000 cars of the same model will have a manufacturing defect?

• 150

• 200

• 250

• 300

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.MD.A.2

What is the constant (k) in this inverse variation?
y = 400/x

• x
• y
• 400
• Not enough information given

Tags

CCSS.HSA.SSE.A.1

CCSS.HSF.BF.A.1