Express GST

Purpose

The purpose of this task is to engage students in expressing a percentage as a fraction and to be able to apply this as a multiplier.

Description of Mathematics

This background knowledge and skills that need to be established before and/or during this task are outlined in the diagram below:

This task may be explored using a variety of different numerical explorations. The approach should be chosen in sympathy with their skills and depth of understanding of operations on fractions, decimals and percentages.

Activity


Task: An old maths worksheet had a 'quick calculation trick' for working out the GST to add to the price of a product. The quick calculation said to multiply the GST exclusive price by 11/10.

  1. Was this quick calculation for when GST was, 10%, 12.5% or 15%?
  2. What would the fractions be for quick calculations for each GST value; 10%, 12.5% or 15%?
     

The procedural approach (show more)

  • The student is able to express a GST inclusive price as a product of the exclusive price and a decimal.

The conceptual approach (show more)

  • The student is able to express a GST inclusive price as a product of the exclusive price and an improper fraction.

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