Number And Algebra - Chapter 7 Applying Ratios And Rates - Nelson Think Math Page 13
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Applying ratios and rates
The unitary method can also be used for ratios with more than two shares.
Example
11
Worksheet
A jar containing 450 g of curry powder has the spices chilli, coriander and turmeric in the
Ratio applications
ratio 2 : 4 : 3. How much of each spice is in the mixture?
MAT08NAWK00047
Solution
TLF learning object
Work out the total number of parts.
Total parts ¼ 2 þ 4 þ 3
In proportion: ratios
¼ 9
(L8098)
Value of one part ¼ 450 4 9
Calculate the amount for one part.
MAT08NAIN00007
¼ 50 g
TLF learning object
Calculate the chilli.
Chilli ¼ 2 parts
In proportion: variables
¼ 2 3 50 g
in ratios (L8101)
¼ 100 g
MAT08NAIN00007
Calculate the coriander.
Coriander ¼ 4 parts
¼ 4 3 50 g
¼ 200 g
Calculate the turmeric.
Turmeric ¼ 3 parts
¼ 3 3 50 g
¼ 150 g
Check the total.
Total amount ¼ 100 þ 200 þ 150 g
¼ 450 g
OK
Write the answer.
The curry powder consists of 100 g of chilli,
200 g of coriander and 150 g of turmeric.
Two jellybean makers both claimed to have ‘more black beans’ than any other brand. Over the
years, the makers argued about which one had more black beans. To settle the row, they decided
to each open one of their packets and do a count.
Beanie
Beans — 48 black and 64 others
Bongo
Beans — 39 black and 52 others
Black : total
Black : total
¼ 48 : ð48 þ 64Þ
¼ 39 : ð39 þ 52Þ
¼ 48 : 112
¼ 39 : 91
¼ 48 4 16 : 112 4 16
¼ 39 4 13 : 91 4 13
¼ 3 : 7
¼ 3 : 7
The ratios are the same! So neither could rightly claim to have more black beans.
Important!
Equivalent ratios
Ratios that are the same are called equivalent ratios. Ratios can be shown to be equivalent by:
• multiplying or dividing each part of one ratio by the same number to get the other or
• cancelling both to the simplest form or
• cross-multiplying to get the same answer.
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9780170214148
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