Inverse 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

The cost per person to rent a mountain cabin varies inversely to the number of people who share the rent. If the cost is $36 per person when 5 people share, what is the cost per person when 8 people share?

• $22.50

• $57.60

• $4.50

• $12.50

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

• x

• y

• 400

• Not enough information given

Given that y varies inversely with x, if x =7 and y = 4, what is y when x = 2?

• 14

• 10

• 2

• -14

An ​ (a)   takes a previously found result ( a y value) and returns it to its original value (x value). This means you are ​ (b)   a function

• function

• inverse

• 2 or more

• undoing

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 

Which of the following represents indirect variation?

• y = kx

• y = k/x

• y = x/k

• y = mx + b

Suppose p varies directly as r, and p varies inversely as t.
t = 20 when p = 4 and r = 2.
Find t when r = 10 and p = -5.

• 80

• -80

• 4

• -20

What does the following equation represent ?  xy=7

• Direct variation

• Inverse variation

• neither

Given: y varies inversely with x. If y = 40 when x = 16, find x when y = -5. Find the value of x.