Example 3

A school supply company produces wooden rulers and plastic rulers. The rulers must first be made, and then painted.
  • It takes 20 minutes to make a wooden ruler. It takes 15 minutes to make a plastic ruler. There is a maximum amount of 480 minutes per day set aside for making rulers.
  • It takes 5 minutes to paint a wooden ruler. It takes 2 minutes to paint a plastic ruler. There is a maximum amount of 180 minutes per day set aside for painting rulers.
Write a system of inequalities that models the constraints involved in the making and then painting of wooden and plastic rulers.
  1. Identify the information you know.
  2. Write an inequality using variables to represent the amount of time needed to make the rulers.
  3. Use the same variables to write an inequality to represent the amount of time needed to paint the rulers.
  4. Determine the constraints on this situation, then write inequalities to represent these constraints.
  5. To write the system of inequalities for this situation, combine all the inequalities related to the situation and list them in a brace, {.
This applet is provided by Walch Education as supplemental material for their mathematics programs. Visit www.walch.com for more information on their resources.