Applications of Direct & Inverse Variation

 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 width of a rectangle varies inversely with its length.  If the width is 6 when the length is 24, give an equation that shows the relationship.

• y = 4x
• y = 144x
• y = 4/x
• y = 144/x

Tags

CCSS.HSA.CED.A.2

CCSS.HSF.BF.A.1

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

The interest received on a savings account varies directly with the amount deposited. Daniel received $55.35 in interest on $1230 he deposited. How much interest would Daniel have received if he had deposited $2000 into his account?

• 34.04
• 90.00
• 1,285.35
• 44,444.44

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

 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

a varies inversely as the square of b. If a is 1 when b is 3, find a when b is 5. 

• 0.36
• 9
• 25
• 36

y varies directly as x, if y=12 when x=5, find y when x=3

• 36/5
• 15/12
• 12/5
• 12/15

y varies directly as x, if y=4 when x=3, find x when y=-12

• -16
• 16
• -9
• 9

Tags

CCSS.8.EE.C.7

CCSS.8.F.A.3

CCSS.8.F.B.4