Home >> Number  Ratio & Proportion
[ dividing by ratio ][ proportional change ]
Simple Ratios  A ratio is a way of comparing the relative magnitude of different quantities.
A, B, C 20 : 30 : 50
Simplification of Ratios  Division by a common factor or factors reduces the size of numbers used in a ratio.
20 : 30 : 50 becomes 2 : 3 : 5
examples:
20 : 55 becomes 4 : 11 (dividing by 5)
39 : 12 becomes 13 : 4 (dividing by 3)
56 : 24 becomes 7 : 3 (dividing by 8) 
Dividing by Ratio  This is the method to follow:

Example #1  Divide 90 in the ratio 3 : 2
total of ratio numbers = 3 + 2 = 5
Therefore 90 shared in the ratio 3 : 2 is 54 and 36
Example #2  Divide 132 in the ratio 6 : 5
total of ratio numbers = 6 + 5 = 11
Therefore 132 shared in the ratio 6 : 5 is 72 and 60
Example #3  Divide 288 in the ratio 2 : 6 : 4
total of ratio numbers = 2 + 6 + 4 = 12
Therefore 288 shared in the ratio 2 : 6 : 4 is 48, 144 and 96
Proportional Change is when a quantity is increased or decreased by multiplication with the numbers of a ratio expressed as a fraction.
The first number of the ratio becomes the numerator, while the second becomes the denominator.
Example #1  increase 56 in the ratio 3 : 2
Example #2  decrease 72 in the ratio 4 : 9
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