Direct and Inverse Variation

• direct variation
• inverse variation
• joint variation
• none of these

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

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

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

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

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 

What kind of equation is this?
xy=8

• Linear Equation

• Direct Variation

• Inverse Variation

• Joint Variation