Computer games

Computer games

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Overview
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Further Resources
This task is about working out costs with multiplication and percentages.
The information below shows the costs of buying some computer games from the United States (U.S.) through a mail-order computer company.
Computer Game Cost
1 to 4 games $55 each
5 to 24 games  $45 each
25 to 49 games $40 each
Postage and Handling Cost (P&H)
P&H cost of first game: $5 for deliveries within the U.S.
  $7 for deliveries outside the U.S (overseas).
P&H cost of additional games: $1 each
Tax Cost: Californian residents ONLY, please add 7% tax on the total cost (including P&H cost).
Note: All prices are in U.S. dollars (US$)

Question 2Change answer

a)  How much would it cost to buy one computer game, including P&H,
     if someone lived in the United States somewhere other than California?  US$ 

Question 2Change answer

b)  How much would it cost a person living in New Zealand to buy,
     including P&H, 26 computer games?  US$ 

Question 2Change answer

c)  How much would it cost a person living in California to buy, including P&H, 
     i)  one computer game? US$ 
     ii) 7 computer games? US$ 
Task administration: 
This task can be completed with pencil and paper or online with auto-marking.
Level:
5
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
multiplication, addition, percentages, money
Description of task: 
Students perform addition, multiplication, and percentage calculations based on information about the cost of buying and posting computer programs.
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 (10/1998)
a)   $60 easy
b)   $1072 very difficult
c) i)
ii)		 $64.20
$348.82		 moderate
very difficult
Diagnostic and formative information: 
  Common error Likely calculation Likely reason
a)
c) i)		 $62
$66.34		 55 + 7
(55 + 7) × 1.07		 Uses overseas price for P&H.
b)

c) ii)

 $45
or 47
$53.50
or $55.64		 40 + 5
40 + 7
(45 + 5) × 1.07
(45 + 7) × 1.07
Assumes total price for several programs (inc. P&H) is same
as for one program.
b)
c) ii)		 $1047
$342.40		 (40 × 26) + 7
(45 × 7 + 5) × 1.07		 Ignores P&H for all but first program.
NOTE: These errors are sometimes combined to create other answers (e.g., uses overseas price and ignores P&H for all but first program).