Real World Problems Linear Functions

Joe had a summer job that pays $7.00 an hour and he worked  between 15 and 25 hours every week. His weekly salary can  be  modeled by the equation:   y = 7x, where y is his weekly salary and  x is the number of hours he worked in a week. What is a reasonable domain for this function?

• {15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25}

• {105, 112, 119, 126, 133, 140, 147, 154, 161, 168}

• {x | 15 ≤ x ≤ 25}

• {x | 105 ≤ x ≤ 168}

What is a possible range for this situation?

• {1,2,3,4}

• {75,125,175,225}

• {𝑥 | 1 ≤ 𝑥 ≤ 4}

• {𝑦 | 25 ≤ 𝑦 < 225}

A plumber charges a $25 service fee and $50 per hour for at least one hour but not more than 4 hours. If 𝑥 represents the number of hours the plumber is at your house, the total cost for the plumber’s service is represented by 𝑓(𝑥) = 50𝑥 + 25.

What is a possible domain for this situation?

• {1,2,3,4}

• {75,125,175,225}

• {𝑥 | 1 ≤ 𝑥 ≤ 4}

• {𝑦 | 25 < 𝑦 < 225}

The total cost, 𝑐, in dollars to create calendars for a fundraiser can be found using the function 𝑐 = 5.5𝑢 + 25 where u is the number of calendars made. If there are at least 10 calendars made, what is a possible domain for this function?

• {𝑥 | 0 ≤ 𝑥 < 50}

• {−12,−11,12,20,50}

• {𝑥 | 10 ≤ 𝑥 < 100}

• {10,11,12,13,14}

• A

• B

• C

• D

(a)  

• A

• B

• C

• D

Click on picture for question.

• A

• B

• C

• D

Greg sells cars. He makes a base salary of $25,000, plus $1500 per car he sells. The function that models this situation is S = 1500x + 25000. After working at the car dealership for 2 years, he gets a raise. He now makes $1700 per car he sells. What is the new function that models this situation?

• S = 1700x + 1500

• S = 1500x + 1700

• S = 1700x + 25000

• S = 25000x + 1700

A carnival charges $2.50 per ride. It also costs $20.00 to enter the carnival. Which linear function models the total cost, t, of a day at the carnival going on r rides?