Ratios and proportions are equal ratios. If two ratios are equal, the quantities are in proportion. Proportions say that two fractions or ratios are equal. Examples show that ratios being equal means the relative sizes are the same, so they are proportional. Several examples demonstrate ratios being equal and therefore proportional, such as numbers of males to females in different groups or hours worked to wages earned. A review question asks if the shades of blue in paint mixtures will be the same if the ratios of ingredients are equal. An assignment involves calculating ratios of investments and profit shares to determine if they are proportional.

2. RATIO AND PROPORTION

3.  If two ratios are equal ,then the numbers or
values in the ratio are said to be in proportion

4. Proportion says that two ratios
(or fractions ) are equal
Example :

5.  When things are “ in proportion “ then their relative sizes are the
same
Here you can see that the
ratios of head length to body
length are the same in both
drawings.
So they are proportional.
Making the head too long or
short would look bad!

6. OBSERVE
= 1/2 =2/4
= 4/ 8
All these are in proportion

7.  There are 6 males and 2 females in a car.
 There are 27 males and 9 females in a bus.
o Ratio of men = 6/ 27 = 2/9
o Ratio of female = 2/ 9
Both the ratios are same, so they are
proportional.

8.  Ramu worked 8 hours and got 400 rupees as wages. Benny
worked 6 hours and got 300 Rupees. Are the wages proportional
to the hours of work?
Ans :
Ratio of hours of work of Ramu and Benny = 8 : 6
= 4 : 3
Ratio of wages of Ramu and Benny = 400:300
= 4 : 3
Hours of work and wages are proportional

9. Review :
10 litres of blue paint and 15 litre of white paint
are mixed in one can . 12 litre of blue and 17 litre
of white are mixed in another . Will the shades of
blue in the two cans be the same ? Why?

10. Assignment
Mathew invested 30000 rupees and Stephen 50000
rupees to start a business. In one month they
made a profit of 2400 rupees . Mathew took 900
rupees and Stephen took 1500 rupees as their
shares of profit .
 What is the ratio of their investments ?
 What is the ratio of their shares of the profit?
 Are the shares proportional to the investments

11. THANK YOU