This document provides an overview of ratios, proportions, and their properties. It defines a ratio as a comparison of quantities represented using ":" and explains how to obtain a ratio by dividing the first quantity by the second. It describes the terms in a ratio and properties such as ratios being pure numbers without units. Proportions are defined as the equality of two ratios, with the four terms being the extremes and means. Direct proportion is explained as two quantities increasing or decreasing proportionally together, while inverse proportion is two quantities changing proportionally in opposite directions.

1. St. Thomas Training College
Submitted By:
Susan Joseph
Mathematics Optional
Reg no : 18014386011
Year : 2014-2015

2. WELCOME

3. Ratio & Proportion

4. Ratio:
Comparison of quantities is called
ratio.
It is represented using :

5. How to obtain Ratio?
Simply divide the first quantity by the second
Eg: If A=3 , B=2
Ratio between A and B= 3/2 = 3:2

6. Quantities in a Ratio.
Two quantities in a ratio are called its terms.
Eg; 3:2
Here 3 is the first term & 2 is the second
term.

7. Properties of Ratio.
•Ratio is a pure number.
•It has no unit.
•It should be expressed in lowest term.
Eg: Let A=36kg & B=34kg
So, A:B = 36/34 = 3/2 = 3:2

8. Let a:b & c:d be two equivalent ratios
Then, a:b = c:d
a/b = c/d
a*d = b*c

9. Proportion:
Equality of two ratios are called proportion.
‘two in every five’ (this is like a fraction)
What proportion of this shape is red?
four reds out of twelve squares in total
What proportion of this shape is white?
eight whites out of twelve squares in total

10. Quantities in a proportion;
The four quantities which form a proportion
are called its terms.
*The 1st
and the 4th terms are called extremes.
*The 2nd and the 3rd terms are called means.
Eg; 14:30 :: 63:135
means+ = 30, 63
Extremes = 14, 135

11. Direct proportion;
If two quantities are so related to each other,
such that an increase (or decrease) in the
first quantity causes a proportional increase
(or decrease) in the second quantity. Then the
two quantities are said to be directly
proportional.
Eg: Age & Years

12. Inverse proportion
If two quantities are so related to each other,
such that an increase (or decrease) in the
first quantity causes a proportional decrease
(or increase) in the second quantity. Then the
two quantities are said to be inversely
proportional.
Eg; Speed & Time

13. Thank You