Inverse and Direct 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

Is the given table a direct variation? If so, what is the constant of variation?

• Yes. k = 1/3

• Yes. k = 3

• Yes. k = 5

• No

Which of the given graphs is a direct variation?

• A

• B

• C

• D

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 (x) by 6 painters (y). 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

Trina's paycheck earnings varies directly as the number of hours she works. If she works 19 hours (x) and earns $187.15 (y), what should she earn if she worked 40 hours?

• $394

• $443.25

• $472.80

• $512.20

y varies directly as x. If y = 15 when x = 12 find y when x = 32.

• 40

• -40

• 5

• -5

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

• y = 4x

• y = 144x

• y = 4/x

• y = 144/x

The height of a wave on the Atlantic Ocean varies directly with the seconds that pass by. At 4 seconds (y), the wave is 6 feet high (x). How many seconds will give you a wave that is 10 feet high?

• y = 2/3x

• 6

• 6.6

• 7

The interest received on a savings account varies directly with the amount deposited. Daniel received $55.35 (y) in interest on $1230 (x) 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