Direct and Inverse Variation

Suppose y varies directly as x.
If  y = 22.5 when x = 15, find y when x = 20.

• 1.5
• 337.5
• 30
• 16.875

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

• 300
• 75
• 1,875
• 12

Which of the following represents direct variation?

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

Which of the following represents indirect variation?

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

 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

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

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

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

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

• 300
• 75
• 1,875
• 12

 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