NCERT Book Class 6 Maths Chapter 12 Ratio and Proportion

Ratio and
Proportion

Chapter 12
12.1 Introduction

In our daily life, many a times we compare two
quantities of the same type. For example, Avnee and
Shari collected flowers for scrap notebook. Avnee
collected 30 flowers and Shari collected 45 flowers.
So, we may say that Shari collected 45 – 30 = 15
flowers more than Avnee.
Also, if height of Rahim is 150 cm and that of
Avnee is 140 cm then, we may say that the height of
Rahim is 150 cm – 140 cm = 10 cm more than Avnee.
This is one way of comparison by taking difference.
If we wish to compare the lengths of an ant and a
grasshopper, taking the difference does not express
the comparison. The grasshopper’s length, typically
4 cm to 5 cm is too long as compared to the ant’s
length which is a few mm. Comparison will be better
if we try to find that how many ants can be placed
one behind the other to match the length of
grasshopper. So, we can say that 20 to 30 ants have
the same length as a grasshopper.
Consider another 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 and if we compare by division;
2,50, 000 5
i.e. 50, 000 = 1