Direct & Inverse Variation

The value of y varies directly with x.  Which function represents the relationship between x and y if y = 14 when x = 6. 

• y=20x
• y=84x
• y=7/3x
• y=3/7x

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CCSS.HSA.CED.A.2

CCSS.HSA.SSE.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

 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.7.RP.A.2B

The Height of a wave in California varies directly with the seconds that pass by.  At 4 seconds, the wave is 6 feet high.  How many seconds will give you a wave that is 10 feet high? 

• y = 2/3x
• 6
• 6.6
• 7

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.REI.B.3

CCSS.HSA.SSE.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.2

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

 Y varies inversely with x, and y is 0.5 when x is 4. Which equation represents this situation?

• y=2x
• y=2/x
• y=4x
• y=x/2

Tags

CCSS.HSA.CED.A.2

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.2

y varies directly with the square of x.  If y=40 when x=4, find y when x = 7

• 17.5
• 70
• 122.5

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.2

CCSS.HSA.SSE.A.1

y varies directly as the square of x and indirectly with z. If y is 8 when x is 4 and z is 6, find y when x is 8 and z is 4.

• 3
• 12
• 48
• 64

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.2

CCSS.HSA.REI.A.1

CCSS.HSA.SSE.A.1

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

Boyle’s Law states that, for a fixed amount of gas, the volume of the gas at a constant   temperature is inversely proportional to the pressure. If a certain gas occupies 9.84 liters   at a pressure of 50 centimeters of mercury (cm Hg), what is the approximate pressure   when the volume is increased to 12 liters?

• 39.8 cm Hg
• 41.0 cm Hg 
• 43.2 cm Hg
• 45.1 cm Hg

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.2

CCSS.HSA.CED.A.4

CCSS.HSA.REI.B.3

Suppose y varies inversely with x.
If y = 150 when x = 2, find y when x = 25.

• 300
• 75
• 1,875
• 12

Tags

CCSS.HSA.CED.A.1