Direct Inverse Jointly Variations

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

Determine if the relationship between the two quantities is a direct variation. Explain your reasoning.

• yes, the constant of variation is 1/2

• yes, the constant of variation is 2

• no, there is constant of variation.

What is the constant (k) in this inverse variation?
y = 400/x

• x

• y

• 400

• Not enough information given

y is inversely proportional to x, and y = 8 when x = 3

What is the equation?

• y = 24x

• y = 24/x

• y = 24

• x = 24

Write an equation

The cost C of fish varies directly as its weight w in kilogram.

• C =kw

• W=kc

• K= Cw

• K =w/c

Is the following graph direct, inverse, or neither?

• Direct

• Inverse

• Neither

varies jointly as x and y and z = 60 when x = 5 and y = 6.

Find z when x = 7 and y = 6

• 84

• 60

• 24

• 30

Write an equation for the given relationship.

x varies directly with y and inversely with z.

Tags

Variations

What type of variation does this scenario represent?

The grade you earn in a class and the number of assignments you complete and the number of hours you study.

• direct

• inverse

• joint

• combined

Tags

Variations

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