Direct, Inverse and Joint Variation

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

• x
• y
• 400
• Not enough information given

Determine the type of variation:

• Direct
• Inverse
• Neither

Which of the following represents indirect variation?

• y = kx
• y = k/x
• y = x/k
• y = mx + b

If y varies inversely as x and x=5 when y=20, then what is the constant of variation, k? 

• 121
• 4
• 100
• 6

The cost per person to rent a mountain cabin is inversely proportional (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
• $1.11
• $12.50

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

• Direct, 12
• Inverse, 12
• Direct, 1/12
• Inverse, 1/12

If y = 15 when x = 32 find y when x = 12.

• 40
• -40
• 5
• -5

Assume y varies inversely with x. If x=7 when y=4, what is y when x=2 ?

• 4
• 14 
• 7
• 28

 y varies directly with x.
 y is 84 when x is 16. What is the constant of proportionality?

• y = (21/4)x
• k = 21
• k = 5.25
• k = 4/21

In a direct variation, y = 39 when x = 3. 
Find the value of y when x = 2.

• 26
• 3
• 58.5
• 2