Computer repairs

Computer repairs

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about solving word problems.
computer, monitor and keyboard
 
 
Three families used different companies to get their computers fixed.

 

Question 1Change answer

a) The Borland family had their computer fixed. Here are the costs for getting this done.
  • $60 for the pickup and return of the computer
  • $30 for parts
  • $60 for each hour it took to fix.
    The Borland family's computer took 5 hours to fix. How much did this cost in total? $ 

Question 2Change answer

b) The Tupaki whānau had their computer fixed. Here are the costs for getting this done.
  • $30 for the pickup and return of the computer
  • $50 for parts
  • $80 for each hour it took to fix.
    If the total cost was $320, how many hours' work were requried to fix it? 

Question 3Change answer

c) The Kingi family had their computer fixed. Here are the costs for getting this done.
  • Free pickup and return of the computer
  • $45 for parts
  • $100 for each hour it took to fix.
    If the total cost was $295, how long did it take to fix it? 
Task administration: 
This task can be completed with pencil and paper or online (with some auto-marking).
Level:
4
Curriculum info: 
Maths, Number and Algebra, Equations and expressions
Keywords: 
linear equations, money
Description of task: 
Students use linear equations to help them solve word problems about the cost of computer repairs.
Learning Progression Frameworks
This resource can provide evidence of learning associated with
Using symbols and expressions to think mathematically, sets 4-5
within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
  

Y8 (09/2000)

a)

390

easy

b)

3

moderate

c)

Any 1 of:

  • 21⁄2 hours
  • 2.5hours
  • 2 hours 30 minutes
  • 150 minutes

moderate
Diagnostic and formative information: 
 

Common error

Likely reason

a)
b)

$150
4

Calculation done for only one hour.
Ignores pickup, return and parts costs ($50 + $30).
Next steps: 

Extension:

Mrs Daniels wanted to get her computer fixed. No parts were needed. All three firms would charge her the same total amount for repairs (including pickup and return).

  1. How long would Mrs Daniels repairs take? (Answer: 1.5 hours)
  2. Plot a graph of how much each firm would charge in total for a variety of different times to fix computers if there were no parts needed. What do you notice about the three graphs. (Answer: They are straight lines that meet at the point (1.5, 150).)