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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.
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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.
Which bag of Easter eggs is the better value? $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. • 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
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
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.
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?
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
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.
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.
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.
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
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!
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?