Modeling Systems of Inequalities

Madelyn has x quarters (each are 25 cents) and y dimes (each are 10 cents). She has no less than 18 coins worth at most $3.60 combined. Write a system of inequalities that represents this scenario.

Mike wants to fence in part of his backyard. He wants the length of the fenced-in area to be at least 20 feet long, l ≥ 20. He has 200 feet of fencing. The inequality that models the possible perimeter of the yard is 2l + 2w ≤ 200. Which are possible dimensions for Mike’s backyard? Check all that apply.

• w = 50 ft; l = 10 ft

• w = 10 ft; l = 50 ft

• w = 20 ft; l = 60 ft

• w = 90 ft; l = 30 ft

• w = 50 ft; l = 40 ft

Erin and her friends are taking a road trip. She has agreed to drive between hours 3 and 6 of the trip. If h represents the hours of the trip Erin will be driving, then h ≥ 3 and h≤ 6 represents her portion of the driving. While she is driving, her distance and time are modeled by the inequality d < 70h. What are the possible hours and distances Erin could be driving? When graphing this scenario, let h be the horizontal variable and d be the vertical variable. For the inequality h ≥ 3, the graph should ____________ be the boundary line.

• Shaded Above

• Below

• To the right of

• To the left of

Erin and her friends are taking a road trip. She has agreed to drive between hours 3 and 6 of the trip. If h represents the hours of the trip Erin will be driving, then h ≥ 3 and h≤ 6 represents her portion of the driving. While she is driving, her distance and time are modeled by the inequality d < 70h. What are the possible hours and distances Erin could be driving? When graphing this scenario, let h be the horizontal variable and d be the vertical variable. For the inequality h≤ 6, the graph should ____________ be the boundary line.

• Shaded Above

• Below

• To the right of

• To the left of

Kim wants to earn at least $65 from her two jobs next week. At most, she can work 15 hours. Her first job pays $5 per hour, and her second job pays $7 per hour. Let x represent the number of hours worked at the first job and y represent the number of hours worked at the second job. Which system of linear inequalities models Kim's situation?

Which system of inequalities is represented by this graph?

• y < -3x + 3 and y > -3x - 1

• y ≥ -3x + 3 and y ≤ -3x - 1

• y ≤ -3x + 3 and y ≥ -3x - 1

• y > -3x + 3 and y < -3x - 1

A carpenter has $60 with which to buy supplies. The carpenter needs to buy both nails and screws. Nails cost $12.99 per box, and screws cost $14.99 per box. If n represents the number of boxes of nails and s represents the number of boxes of screws, which of the following systems of inequalities models this situation?

• {12.99n+14.99s $\le$ 60
  
  {n $\ge$ 1
  
  {s $\ge$ 1

Which system of inequalities is shown?

• y ≥ -x - 1
  y < x + 4

• y < -x - 1
   y ≥ x + 4

• y > -x - 1
  y ≥ x + 4

• y > -x - 1
  y ≥ x + 3

Your taxi fare is $2.50 per mile, plus a $5 fee.  You cannot exceed $20.  Which inequality models this scenario?

• 5x + 2.50 ≤ 20

• 2.50x + 5 < 20

• 2.50x + 5 ≤ 20

• 7.50x < 20

Anita is saving for college and wants to take no fewer than $3000 with her for the fall semester. Her summer job pays $9/hour. She has already saved $720. How many hours will Anita have to work during the rest of the summer to meet her goal? Select the inequality that models the situation if h represents the number of hours Anita will need to work.