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Its simple! All you have to do is: Convert each price to a price per kilogram. [Or price per litre...

Date post: 15-Dec-2015
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Page 1: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.
Page 2: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

Its simple!

All you have to do is:

Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]

Then choose the cheapest price.

Note! There are several different ways to do the maths. This PowerPoint shows only one of the ways.

Page 3: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

Which bag of Easter eggs is the better value? The purple packet costs

$9.98 for 475g or $22.59 per kg

The red packet costs $3.48 for 180 g or $20.78 per kg

$20.78 for 1 kg is less than $22.59 for 1 kg.

The red 180g packet is better value for money.

The smaller packet is the better value.

Page 4: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

A 500g bag of pasta costs $3.65. What is the price per kilogram?

500g + 500 g = 1000g

Two bags of pasta contain 1000g or 1 kg.

$3.65 + $3.65 = $7.30

Or 2 × $3.65 = $7.30

The price per kilogram is $7.30

Page 5: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

Which packet of rice is the better value?

Two 500g packets make 1kg.

$2.10 × 2 = $4.20

In the 500g packet the rice costs $4.20 per kg.

In the 5 kg pack one kg of rice costs $22.60 ÷ 5 = $4.52

$4.20 is cheaper than $4.52.

The 500 g packet is the better value.

Page 6: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

A 375 ml can of soft drink is priced at $1.40. Calculate the price per litre.

Two cans of drink contain 2 × 375 ml = 750 ml.

Three cans contain 3 × 375 ml = 1125 ml

Two and a bit cans hold 1000 ml or 1 litre.

Two cans is not enough and three cans is too many.

Exactly how many cans do I need?

Page 7: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

Exactly how many cans do I need?

1 L is the same as 1000 mL.

I will need cans to make 1 litre.

1L = 1000 ml

23

1 Litre 375 mL

=1000 375

2

232

Page 8: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

How much will 1 litre costs? Cost of 1 litre = cost for 1 can × number of cans

Cost of 1 litre = $1.40 per can × cans

= $3.73

1 litre will cost $3.73

375 mL for $1.40 is equivalent to $3.73 per litre.

232

Page 9: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

What size Sultana Bran is the best value?

Page 10: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

In the small packet the price of the Sultana Bran is $44.22 per kg.

One small packet weighs 45g.

1000 ÷ 45 =

packets weigh 1 kg

One small packet costs $1.99.

× $1.99 = $44.22

45g for $1.99 is equivalent to $44.22 per kilogram.

2922

2922

2922

Page 11: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

In the 500g box, the price of the Sultana Bran is $11.58 per kilogram.

One 500g packet of Sultana Bran costs $5.79.

Two packets of 500g Sultana Bran make 1 kg.

2 × $5.79 = $11.58

500g for $5.79 is equivalent to $11.58 per kilogram.

Page 12: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

In the 820g box the price of the Sultana Bran is $9.04 per kilogram.

The large 820g box of Sultana Bran costs $7.41.

1000 ÷ 820 =

boxes of 820g sultana Bran make 1 kg.

× $7.41 = $9.04

9411

9411

9411

Page 13: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

45g for $1.99

= $44.22 per kg

500g for $5.79

= $11.58 per kg

820g for $7.41

= $9.04 per kg

The 820g packet is the best value.

The 45g packet is very poor value!

Page 14: Its simple! All you have to do is:  Convert each price to a price per kilogram. [Or price per litre if the item is a liquid.]  Then choose the cheapest.

Summary of how to do the maths Calculate the number of containers required to

make 1 kilogram or 1 litre.

(1000 ÷ size of the container in g or mL)

Calculate the price of 1 kg or 1 L by multiplying the price per container by the number of containers required to make 1 kg or 1 L.

Remember! There are other ways to do the maths. Can you do the calculations a different way?


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