Quantitative Aptitude – Ratio and Proportion
Ratio and Proportion is a type of fractional number, together which represent a same unit of number. In competitive exams ratio is a very important topic. Almost every competitive exams having few questions from this topic. So, students you need to learn this chapter very carefully.
Before begin this chapter you should have a clear knowledge of Fraction number. If you need to learn it then “Click here to learn Fraction number“.
Let’s start this topic.
What is Ratio ?
Definition: A Ratio means How much each object is used to make the whole Unit.
Let’s explain this,
Suppose we have 30 children in a Classroom. (This is the whole unit)
Now out of those 30 children their is 12 Boys and 18 Girls. (Boys and Girls are two objects)
So the Ratio of Boys and Girls in that classroom is 12 : 18. (We use : to represent ratio)
Scaling Ratio: We can also scale Ratio value to up or down. I the previous example we get 12 : 18 as our ratio value. But we can further scale this value down.
- 12 : 18 = (12/6) : (18/6) = 2 : 3
So, we can also write 12 : 18 as 2 : 3. Similarly we can also upscale the value and write it as 24 : 36.
What is Proportion ?
Definition: When we write a statement where two different ratio are equal, that is called Proportion.
Let’s explain this,
From the previous example we learned that we can scale down 12 : 18 into 2 : 3. So here ratio 2 : 3 is equal to ratio 12 : 18. Or we can say that 2 : 3 is a proportion of 12 : 18.
We write it as- 2 : 3 = 12 : 18 or
2/3 = 12/18
One more thing to keep in mind is, when two ratio is equal then the cross product of the ratio is also equal.
2/3 = 12/18
or, 2 x 18 = 12 x 3
or, 36 = 36
This is the basics of Ratio and Proportion. If you want to read more about ratio and proportion then find a good book of ratio and proportion or simply google it. You can ask your question here. Our member of www.AptitudeTricks.com will answer your questions.