Writing and interpreting functions

Ounces of medication vary directly with the weight of the patient. If a 120-pound adult requires 3 ounces of a medication, how many ounces would be needed for a 200-pound adult?

• 2 ounces

• 3 ounces

• 5 ounces

• 9 ounces

In a joint variation, y = 105 when x = 5 and z = 7.

Find the value of y when x = 9 and z = 10.

• 270

• 180

• 360

• 255

If y varies inversely with x, and y = 6 when x = 2, find y when x = 4.

• 4

• 2

• 3

• 1

The gallons of water used to take a shower varies directly with the number of minutes in the shower. If a 6 minute shower uses 36 gallons of water, how many minutes was a shower that used 90 gallons of water?

The value of y varies directly with x. If x = 3, then y = 21. What is the value of x when y = 105?

• 3/5

• 1 2/3

• 7

• 15

The height of a wave in Huntington Beach, CA 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

Answer explanation

In the table, y varies directly with x.

Which equation represents the relationship?

HyVee found that the demand for Coke products varies inversely as the price of the product. When the price of a Coke product is $2.75, the weekly demand is 1250. Find the weekly demand if the price is raised to $4.00.

• 859.4

• 1818.2

• 1604.4

• 723.5

Imagine you're driving a car where the speed is inversely proportional to the time spent driving. Is your speed increasing or decreasing as time goes on?

• Increasing

• Decreasing

• It depends on the time spent driving