Review Direct, Inverse and Joint Variation

• direct variation
• inverse variation
• neither direct nor inverse variation

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

• Yes. k = 1/3

• Yes. k = 5

• Yes. k = 3

• No

Is the given table a direct or inverse variation? What is the constant of variation?

• Direct. k = 12

• Direct. k = 1/12

• Inverse. k = 12

• Inverse. k = 1/12

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

• 9 painters

• 10 painters

• 11 painters

y varies directly with x, and y is 80 when x is 16. Which equation represents this situation?

• y = 4x

• y = 5x

• y = 10x

• y = 1/5x

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

• 40

• 5

• -40

• -5

What type of variation does this scenario represent?

The length of time you charge your cell phone

and the battery power

• direct variation

• inverse variation

• combined variation

• joint variation

What type of variation does this scenario represent?

The outside temperature

and the number of layers of clothes you need to wear outside to feel comfortable

• direct variation

• inverse variation

• joint variation

• combined variation

Suppose y varies inversely with x.

If y = 150 when x = 2, find y when x = 25.

• 300

• 75

• 1875

• 12

Suppose y varies jointly as x & z. If y = -180 when z = 15

and x = -3, then find y when x = 7 and z = -5.

• -140

• -4

• 140

• 4