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Henrico County Public Schools, Virginia
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Module - Solving Inequalities
Introduction - Predicting Elections



Solving Inequalities by Addition and Subtraction


Solving Inequalities by Multiplication and Division


Solving Multi-Step Inequalities


Solving Compound Inequalities


Module Review



During election campaigns, candidates need to know how people in their area will vote. Since it is not possible to speak to all of the voters, candidates use polls to help find this information. A sampling of voters is asked how they will vote and, based on the results, a projection is made on how the election will turn out.

Since the results are projections, the accuracy depends on how many people were asked. The more people that are randomly asked, the better the accuracy of the projections.

Suppose a candidate is projected to get 48% of the votes, and the poll’s results are accurate to within 4%. This means the candidate should receive somewhere between 44% (48% - 4%) and 52% (48% + 4%). Using a compound inequality with x representing the percent of the vote received, we write 44 ≤ x ≤ 52. This means that x is somewhere between 44% and 52%. Will the candidate win? It is too close to know at this time and we will have to wait until the election!!

Upon completion of the activities in this unit, you should be able to:

  • Use the following terms in a written paragraph to describe the key concepts of this unit.
    • compound inequality
    • union
    • intersection
  • Solve inequalities by using addition and subtraction.
  • Solve inequalities by using multiplication and division.
  • Solve inequalities involving more than one operation.
  • Solve compound inequalities and graph the solution sets.
HCPS 2002-