RATIOS AND PROPORTIONS

RATIOS AND PROPORTIONS

Ratio ???

Proportion????

How many?????

• What is the strength of boys in our class?

• What is the strength of girls in our class?

• What is the total strength?

Ratio is Comparison of

• two similar quantities as following

• 10 mangoes and 20 mangoes

• 15 oranges and 20 apples

• 35 Boys and 40 Girls

While writing ratio 4 : 5 (OR) 12 : 20

• The First term is Antecedent

• Second term is Consequent

• If more than one terms are there they are simply called first, second and third terms respectively and continued...

• Ratio symbol is read " Is to "

• Remember to Simplify the terms

While writing ratio should we simlify

yes

Multiple Select

What is the ratio of 50p to 2 Rupees

• 4 : 1

• 1 : 4

• 5 : 1

• 1 : 5

Multiple Select

What is the ratio of 500 : 5000

• 10 : 1

• 1 : 10

• 1 : 9

• 9 : 1

Proportion 2 : 4 = 4 : 8

• On simplification If antecedent and consequents are equal

• Equality of two ratios is called proportion

• Two Equivalent ratios are always proportional

Observe the following

• 11 : 12 and 22 : 24

• 3 : 6 and 18 : 36

• 2:4 and 6 :7

In a Proportion 4 : 5 :: 20 : 25

• Symbol for proportionality is ::

  So we can write 10 :20::20:40 and it can be read like 10 : 20 is as 20 : 40

• First and last terms are called extremes

  Second and third terms are called Means

• If two ratios are said to be equal (or) in proportion Product of extremes must be equal to product of means

• a x d = b x c

Multiple Select

10 : 20 and 20 : 40 are in proportion

• True

• False

Cost of 9 Kg Onions is 720. Cost of 4Kg?

• Can we use Proportion to find the answer?

• If yes Tell how to write the proportionality

Multiple Select

Cost of 9Kg Onions is Rs.720 then Cost of 4Kg Onions? ( In Rs)

• 240

• 180

• 320

• 540

Multiple Select

Cost of 15 Pens is Rs.105, Find the cost of 7 Pens

• Rs.42

• Rs.49

• Rs.56

• Rs.63

If ratios are not in proportion then?

• they are lesser or greater ratios

• You can use inequality symbol to represent their relation.

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