Activity 6: Shopping around (Maths)
1. PLAY the video segment
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In the video, Tye explains that Sophie buys all the latest gear and lives 'like there's no tomorrow'.
Sophie seems to always buy what she wants, regardless of price or quality.
If you want to save money when shopping for food, it's a good idea to compare prices. While it's easy to compare prices for identical items, it's not so easy to compare prices when the same item comes in different quantities. |
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2. ANSWER the following question:
a. Which is cheaper 50g of salt and vinegar chips for 80ยข or 100g for $1.50?
Clearly, the larger packet is better value. When comparing prices, it is easier when one size is a multiple of the other, the 100 gram packet of chips is twice the size of the 50 gram packet.
When this is not the case, you need to find the unit price to compare prices. Finding the unit price means finding the price you would pay for 1 unit of the goods.
For example, compare:
2 litres milk $2.20
1.25 litres milk $1.50
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Unit price |
= |
price for 1 litre |
cost(in cents) |
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quantity (in litres) |
2 litres milk:
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Unit price |
= |
price for 1 litre |
220 |
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2 |
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= |
110c |
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= |
$1.10 |
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1.25 litres milk:
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Unit price |
= |
price for 1 litre |
150 |
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1.25 |
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= |
120c |
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= |
$1.20 |
3. DIVIDE the price by the quantity to get the unit price for the items below:
a. 2 litres of cordial for $3.40
b. 3 kg of potatoes for $4.95
c. 30 metres of cling wrap for $2.99
4. CALCULATE the unit price to identify which is the cheaper product. You can find the table below in the PDF Shopping around .
| Item |
Price |
Unit price |
Best buy |
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Sweet spring mineral water 1 litre
Flow mineral water 1.5 litre |
$2.65
$3.50 |
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Heidi's Mountain muesli 750g
Fodos muesli 500g |
$3.22
$1.90 |
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Heidi's Mountain muesli 750g
Fodos muesli 500g |
$1.20
$1.00 |
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5. Comparing prices can be difficult when the quality or features of the products also vary. DISCUSS : How would you go about comparing the cost of two:
- second-hand cars
- computer packages
- printed T-shirts?
This activity can be found in the NSW Money Stuff Teacher resource book - Mathematics page 18.
Explore additional learning activities (which include extension and revision tasks) in the print resources section under Print resources - Victoria.
Linked Learning Outcomes - NSW
Theme 6: Mathematics in the Community
The student chooses and sequences arithmetic operations to solve problems
Learning Outcomes - Victoria
Victorian Essential Learning Standards (VELS) Discipline-based learning
Domain: Maths
Dimension: Number, Space, Measurement, Chance and data, Structure and Working Mathematically
Level 5
Students use efficient mental and/or written methods for arithmetic computation involving rational numbers, including division of integers by two-digit divisors.
Students formulate conjectures and follow simple mathematical deductions.
Level 6
Students carry out arithmetic computations involving natural numbers, integers and finite decimals using mental and/or written algorithms.
Students choose, use and develop mathematical models and procedures to investigate and solve problems set in a wide range of practical, theoretical and historical contexts.
Learning Outcomes - Western Australia
(Maths)
WM 3.5 Extends tasks by asking further mathematical questions and using problem solving techniques that include those based on developing systematic approaches.
N 8.4 Calculates with whole numbers, money and measures, drawing mostly on mental strategies to add and subtract two-digit numbers and for multiplications and divisions related to basic facts.