Linear Functions Applications

Jacob collects hats.  He has 6 hats already, and he collects 2 hats a week.

• y = 2x + 6
• y = 6x + 2
• y = 2x - 6
• y = 6x - 2

The Roaming Cell Phone Company charges $15.00 per month plus $0.20 per minute of airtime usage.  If Juanita uses x minutes of airtime, what is an equation that can be used to determine her monthly cell phone bill (C)?

• C = 0.20x + 15
• C =15 (0.20x)
• C = 15 + x + 0.20
• C = 0.20 + 15x

Scientists measure the total population of polar bears, y, each year in a refuge. They

discovered an initial population of 78 polar bears and an increase of 9 bears each

year. If x is the number of years after the initial observation, which equation best

models the polar bear population?

• y = 9x + 78

• y = 9(78)x

• y = 78x + 9

• y = 78(9)x

A pizza shop charges $12 per pizza and a delivery fee of $4.99. What equation could be used to represent this situation?

An art studio charges a one-time registration fee, then a fixed amount per

art class. Cora has paid $156 for 7 art classes including her registration fee.

Jose has paid $228 for 11 art classes including his registration fee. Write an

equation to model the cost y for x art classes, including the registration fee.

Answer explanation

The cost of the art classes is $18 per class. The one-time registration fee costs $30 :)

An airplane 32,000 feet above the ground begins to descend at a rate of

2,250 feet per minute. Assuming the plane continues the descend at the

same rate, write an equation to model the height h of the plane, t minutes

after it began its descent. Then find the height of the plane after 6 minutes

into its descent.

• 33,500ft

• 23,000ft

• 20,750ft

• 18,500ft

Suppose the population of a species of insects doubles every year. There are 1600 insects initially. The function for the scenario would be?

• $f\left(x\right)=2x+1600$

• $f\left(x\right)=1600\times2$

• $f\left(x\right)=1600\cdot2^x$

• 9600

• 12,800

• 200

• 8000