Direct & Inverse Variation

Jeff used the relation v = ir to calculate the resistance, r, of a copper wire, where ii is the current and v, the constant potential. Find the relationship between the current in the wire and the resistance of the wire.

• Current in the wire is inversely proportional to the resistance of the wire.
• Current in the wire is directly proportional to the resistance of the wire.
• The relationship is neither inverse nor direct
• None of the above

Find an equation that relates x and y inversely, and y = 5 when x = 4

• y = 20 / x
• y = 5 / x
• y = 5x
• y = 20x

According to Hooke's Law, the force needed to stretch a spring is proportional to the length of the spring stretched. If 41 pounds stretches a spring 3 inches, how much will the spring be stretched by a force of 58 pounds?

• 4.24 inches
• 13.67 inches
• 7.24 inches
• 5.24 inches

The number of hours, h, that mm men take to cut xx trees varies directly as the number of trees and inversely as the number of men. If 5 men can cut 25 trees in 5 hours, then how many men are needed to cut 75 trees in 15 hours?

• 7
• 10
• 5
• 6

The cost of producing pencils varies directly with the number of pencils produced. If the cost of producing 6,000 pencils is $400, then what will be the cost of production for 10,000 pencils?

• $612
• $604
• $600
• $610

Tags

CCSS.7.EE.B.3

CCSS.7.RP.A.2

CCSS.7.RP.A.3

The current in an electrical conductor varies inversely as the resistance of the conductor. What is the current when the resistance is 42 ohms, if the current is 4 amperes when the resistance is 168 ohms?

• 21 amperes
• 17 amperes
• 24 amperes
• 16 amperes

Tags

CCSS.7.EE.B.3

CCSS.7.EE.B.4

If a tank is emptied in 9 minutes by a pump that is pumping at a rate of 300 gallons per minute, how long will it take to empty the tank with a pump that will pump at a rate of 500 gallons per minute?

• 8.4 minutes
• 13.4 minutes
• 5.4 minutes
• 11.4 minutes

"The graph of a direct variation model is a line that always passes through the origin". State whether the above statement is true or false.

• True
• False

If L is a constant, then what type of variation does v = L/T represent?

• direct variation
• inverse variation
• joint variation
• the answer is not here

at constant temperature, the pressure of the quality of gas in a container is inversely proportional to the volume of the container the gas is in.
*when the container's volume is 500 ml, the pressure of the gas is 10 units
*the containers volume can expand.
What is the pressure of the gas when the container expands to 1,250 ml, while the temp is held constant.

• 50 units
• 25 units
• 4 units
• 8 units