# Level 3

## 91574: Apply linear programming methods in solving problems

Updated September 2015. This document has been updated in its entirety to address new issues that have arisen from moderation.

### Solving problems

The problem needs to provide sufficient scope for students to demonstrate and develop their own thinking. If there are parts to the problem, all of the parts need to contribute to the solution. A task with a number of discrete skills-based questions is not appropriate for students to demonstrate evidence of the required levels of thinking.

Students need to make their own decisions about what to do and how to solve problems. An instruction like ‘Sketch the inequality y < 3x – 2’ is inappropriate. Where an assessment task has a series of instructions that lead students through a sequence of steps towards the solution, it is likely that the opportunity for students to demonstrate all levels of thinking will be compromised.

### Expected evidence for Achieved

For Achieved the requirements include selecting and using methods. To be used as evidence a method must be relevant to the solution of the problem.

### Expected evidence for Excellence

For a context where the function to be optimised is parallel to a boundary of the feasible region, students are likely to demonstrate extended abstract thinking by justifying that multiple solutions are possible, and finding possible solutions in context.

### Communicating solutions

At all grades there is a requirement relating to the communication of the solutions. For example, students need to show evidence of the inequalities, the feasible region and the co-ordinates of relevant vertices.

At Achieved, students need to indicate what the answer represents.

At Merit, students need to clearly indicate what they are finding, and their solutions need to be linked to the context.

At Excellence, the students need to explain any decisions they make in the solution of the problem.