Variation Review

Suppose y varies directly as x.
If  y = 22.5 when x = 15, find y when x = 20.

• 1.5
• 337.5
• 30
• 16.875

Suppose y varies inversely with x.
If y = 150 when x = 2, find y when x = 25.

• 300
• 75
• 1,875
• 12

Which of the following represents direct variation?

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

Which of the following represents indirect variation?

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

The Height of a wave in California varies directly with the seconds that pass by.  At 4 seconds, the wave is 6 feet high.  How many seconds will give you a wave that is 10 feet high? 

• y = 2/3x
• 6
• 6.6
• 7

A person’s weekly pay is directly proportional to the number of hours worked. Shawn’s pay is $123.00 for 20 hours of work. What is the constant of variation?

• k = 123
• k = 20
• k = 6.15
• k = 0.16

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

• 14
• 10
• 2
• -14

The current in a simple electrical circuit is inversely proportional to the resistance. If the current is 80 amps when the resistance is 50 ohms, find the current when the resistance is 22 ohms.

• 90 amps

• 100 amps

• 105 amps

• 120 amps

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

z varies jointly with x and y. If x = 5, y = -1, and z = 10. Find z when x = -1/2 and y = 7.

• 5

• 6

• 7

• 8