Discount Phone

Discount Phone

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Further Resources
This task is about finding the best price, and making and justifying a recommendation.
 
illustration: mp3 player

Pere saw the same model of phone in two different places. Their prices are shown below.

Electric Supplies

          Stereo by Mail
  

Write a report for Pere about which firm he should buy from. 

  • Recommend which firm would be cheaper. Justify your recommendation.
  • Show all the working or strategies you used to reach your decision.
a)

 

 Recommendation:

 
 
 
 
 
 
b)
Show how you worked this out.
 
 
 
 
 
 
 
 
 
Task administration: 
This task is completed with pencil and paper only.
Level:
5
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
percentages, discount, money, breakeven points, key competencies
Description of task: 
Students recommend which store offers the cheapest product based on calculations of percentage increase or decrease, and fully justify their answers.
Curriculum Links: 
Key competencies
This resource involves making a recommendation about the best buy, based upon percentage computations.
This relates to the Key Competency: Using language, symbols and text.
For more information see http://nzcurriculum.tki.org.nz/Key-competencies
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Multiplicative thinking, sets 8-9
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
    Y10 (03/2004)
a) Makes a correct recommendation including how much cheaper one store is, e.g.,

  • Electric Stores are $3 cheaper.
  • Electric Stores charge $221 compared with $224.

Makes a correct recommendation but does not say how much cheaper one store is, e.g.,

  • Buy from Electric Stores.
  • Electric Stores are cheaper.

[Conditional marking. Give marks if recommendations are based on reasonable calculations even if they are incorrect]
easy
(recommendation with justification)

easy 

(recommendation with no justification)
b) Electric Stores
Any 1 of: 

  • 260 × 0.85 = 221
  • 260 - 260 × 0.15 = 221
  • 200 - 260 × 15 ÷ 100 = 221
  • other correct working

Stereo by Mail
Any 1 of: 

  • 200 × 1.12 = 224
  • 200 + 200 × 0.12 = 224
  • 200 + 200 × 12 ÷ 100 = 224
  • other correct working

NOTE: Marks should be given even when calculations are not labelled with the relevant store.
moderate 
(fully correct for both stores)
 
moderate
(1 type of error in the calculations or one set of calculations correct)