Writing and interpreting functions

The width of a rectangle varies inversely with its length.  If the width is 6 when the length is 24, give an equation that shows the relationship.

• y = 4x
• y = 144x
• y = 4/x
• y = 144/x

The time (t) it takes to fly from Los Angeles to New York varies inversely as the speed of the plane (s). If the trip takes 6 hours at 900 km/h, which equation models this situation?

• t = 5400s

• t = 5400/s

• t = 150s

• t = 150/s

The width of a rectangle varies inversely with its length.  If the width is 6 when the length is 24, give an equation that shows the relationship.

Which inverse variation equation describes the statement below:

When y=2 and x=9 what is the equation?

• y=4.5x

• y=-4.5x

The gallons of water in a pool varies directly with how many minutes the drain has been open. If there are 300 gallons in the pool after the drain has been open for 2 min, how long will it take for there to be 50 gallons remaining?

• 0.33333 minutes

• 6 minutes

• 20 minutes

• 12 minutes

If y varies directly with x and y = 4 when x = -4, find y when x =7.

• 4

• 7

• -7

• -4

The time (t) required to drive a fixed distance varies inversely as the speed (r). It takes 6 hours at 60 kph to drive a fixed distance. How long would it take to drive the same distance at 40 kph? (unit of measure must be written in small letters: _ hours)

If y is inversely proportional to x and y = 7 when x = 9, find x when y = 14.

• 4.5

• 7.9

• 10.9

• 18

Translate into a variation equation.

The weight W of a body varies inversely with the square of its distance d from the center of the earth.

The time required to complete a job varies inversely as the number of people working. It took 4 hours for 7 electricians to wire a building. How long would it have taken 3 electricians to have done the job?

• 1 hr 43 min

• 5 hr 15 min

• 7 hr 30 min

• 9 hr 20 min