Direct and Inverse Variation

As the speed of a train increases, the amount of time it takes to arrive at its destination decreases. What type of variation exists between the speed of the train and amount of time?

• Direct Variation

• Inverse Variation

• Neither

• Not enough information

Which table represents a direct variation?

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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

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 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

Y is directly proportional to the square of z and inversely proportional to w.

• y=kz²/w

• y=kz/w

• y=w/kz²

• y=w/kz

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