Find the percentage

Find the percentage

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
Items in a clothing store were reduced for a sale.





Write down the percentage each item was reduced by.
 
a)
i)    Shirts that were $39.95 but on sale are $19.95 have been reduced by __________%.
 
ii)   Jackets that were $79.95 but on sale are $63.95 have been reduced by __________%.
 
iii)  Trousers that were $69.95 but on sale are $62.95 have been reduced by __________%.
 
b)
On the final day of the sale, another 20% was taken off the sale price.
 
What is the final day sale price of trousers? $_______________
Task administration: 
This task is completed with pencil and paper only.
Level:
5
Description of task: 
Students calculate the percentage by which clothing prices have been reduced.
Learning Progression Frameworks
This resource can provide evidence of learning associated with within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.
Answers/responses: 
 

Y10 (11/99)

a) i)
ii)
iii)
50-50.07
20-20.02
10-10.01
moderate
difficult
difficult
b)   50.35-50.40 very difficult

NOTE: A bigger range is acceptable for b) because students may round the price to the nearest 10c rather than to the nearest 5c.

Diagnostic and formative information: 
  Common error Likely calculation Likely reason
a) ii)
    ii)
25
11
16 ÷ 63.95 × 100
7 ÷ 62.95 × 100
Calculates percentage of final price rather than initial price.
b) 55.95

48.95

42.95

69.95 × .8

69.95 × .7

62.95 - 20

Correctly calculates percentage using $69.95 rather 
than $62.95.
Correctly calculates a 30% (=10% + 20%) reduction 
from original price.
Subtracts % from $.