Number And Algebra - Chapter 7 Applying Ratios And Rates - Nelson Think Math Page 12
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32N E L S O N T H I N K M A T H S
8
A u s t r a l i a n C u r r i c u l u m
for the
1
5
d
Write the ratio.
4
:
2
6
9
5
Write both as improper fractions.
:
¼
2
6
9
5
Multiply both by 6 to make whole numbers.
3 6 :
3 6 ¼ 27 : 5
¼
2
6
Alternatively, you could just multiply both parts
of the ratio by the LCD (6) on your calculator.
Enter as: 4
1
2
6
.
4
1
/
×6
27
2
5÷6×6
5
and 5
6
6
.
In cases that require a quantity to be divided into shares in a particular ratio, it is simplest to use a
unitary method, finding the value of one part of the total parts of a ratio.
Important!
Unitary method
A unitary method involves two main steps:
1 Calculate the value of a single part of the ratio.
2 Multiply this value by the number of parts to calculate the desired quantity.
Example
10
Animated example
Share $42 in the ratio 3 : 4.
Shares in ratios
Solution
MAT08NAAE00011
Total parts ¼ 3 þ 4
Work out the total number of parts.
Scientific calculator
¼ 7
exercise
Value of one part ¼ $42 4 7
Applying ratios and
Calculate the amount for one part.
rates
¼ $6
MAT08NASC00005
First share ¼ 3 parts
Calculate the first share.
Technology worksheet
¼ 3 3 $6
Excel worksheet:
¼ $18
Applying ratios
Second share ¼ 4 parts
Calculate the second share.
MAT08NACT00009
¼ 4 3 $6
Video tutorial
¼ $24
Dividing a quantity
Total amount ¼ $18 þ $24
Check the total.
in a given ratio
¼ $42
OK
MAT08NAVT10020
Write the answer.
The amount is shared as $18 : $24.
249
9780170214148
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