Buying retro CDs and DVDs

Buying retro CDs and DVDs

Auto-markingPencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about working out costs.
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Mr Toimata was buying some retro CDs and DVDs.

Question 1Change answer

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a)  If each CD cost $12.65, how much will a box of 8 Sing-along CDs cost him?
     $ 

Question 1Change answer

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b)  If each CD costs $11.65, how much will a set of 6 Jazz CDs cost him?
     $ 

Question 1Change answer

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c)  If a set of 4 aerobic DVDs cost $54.60, how much does each DVD cost?
     $ 
Task administration: 
This task can be completed with pencil and paper or online (with auto marking displayed to students).
Level:
4
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
multiplication, division, decimals, money
Description of task: 
Students calculate the cost of multiple CDs given the unit cost for a single CD.
Curriculum Links: 
This resource can help to identify students' ability to apply additive or simple multiplicative ideas flexibly to combine or partition decimal numbers to solve multiplication and division problems.
 
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Multiplicative thinking, sets 6-7
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y6 (11/1996)

Y7 (11/1996)
a) $101.20 easy easy
b) $69.90 easy easy
c) $13.65 moderate moderate
Diagnostic and formative information: 
 
Diagnostic information
  Common errors Likely calculation Likely misconception
a)
b) 		 $101.7
$70.7		   Cents shown incorrectly.
a) 
b) 
c) 		 $4.65
$5.65
$50.60		 $12.65 - 8
$11.65 - 6
$54.60 - 4		 Cannot apply appropriate arithmetic operation to the problem.
a) 
b) 		 $1.58
 		 $12.65 ÷ 8
 		 Misinterprets question.
c)  $21.84 $54.60 × 0.4 Confuses division and decimals.