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SAI International School

CLASS – VI

Mathematics

Chapter-12: Introduction to Ratio -1
Lesson Notes - 1

SUBTOPICS:

1) Introduction to Ratio
Methods of comparison
a) Comparison by finding the difference
Example- Cost of a car is 2, 50,000 and that of a motorbike is 50,000.
If we calculate the difference between the costs, it is 2, 00,000
b) Comparison by division

Example- If we compare the above cost by division, i.e =

Hence, the cost of the car is five times the cost of the motorbike.
In the above example, we compared the two quantities in terms of ‘how many times’.
This comparison is known as the Ratio.
We denote ratio using symbol ‘:’
N.B:
 Ratio is comparison by division.
 Ratio compares two or more things of same kind.
 The ratio of two quantities a and b of same units can be denoted in form of

fraction as or a : b (read as a is to b)

st
 In the term a:b we call a = antecedent (1 term)
nd
b = consequent (2 term)

 Two quantities can be compared only if they are in the same unit.

2) Same ratio in different situations (EQUIVALENT RATIO) :
Two ratios are equivalent, if the fractions corresponding to them are equivalent.
Case -1: Length of a room is 30 m and its breadth is 20 m.

So, the ratio of length of the room to the breadth of the room = 30:20 = = = 3:2

Case -2: There are 24 girls and 16 boys going for a picnic.