RATIO AND PERCENTAGE

Meaning of Ratio

The relation between two quantities (both of the same units) obtained by dividing one quantity with another is called ratio. Ratio can be denoted by using the symbol ( : ).

EXAMPLE 1 

What is the ratio between the weight two bags of sugar of 4kg and 6kg respectively?

Solution

Ratio of weights of bags of sugar = 4kg/ 6kg = 2/3 = 2:3

EXAMPLE 2

A pole of length 165cm is divided into two parts such that lengths are in the ration 7:8. Find the length of each part of the pole?

Total ratio = 7 + 8 = 15

First part = ^7/₁₅ , second part = 8/15

Length of first part = 7/15 of 165cm

=  7/15 × 165

= 7 x 11  = 77cm

1 x 1

Light of second part = 165cm – 77cm = 88cm

 

DIRECT PROPORTION

Examples

1. A marker costs $18. Calculate the cost of 5 markers.
2. A student went to the market to purchase textbooks. He purchased two textbooks for $24

• What is the price of one notebook?
• What would be the price of 5 such note

 

Solution

1. If one marker = $18

5 markers       =  $18 x 5 = $90

 

2. 2 textbooks = $24

1 textbook = m

2 × m = 1 x $24

2m = $24

M = $24 ÷ 2 = $12. Therefore 1 textbook = $24

 

(b)  Since 1 textbook = $12

5 textbooks = $12 × 5 = $60

 

EVALUATION

1. What is ratio?
2. Find the ratio of each of the following in its lowest terms:

• 24cm: 72cm
• 425km: 750km
• 75min: 150min
• 85kg: 102kg

3. A field is 50m in length and 60m in width. Find the ratio between its width and length.
4. A scooter can travel 225km with 5 litres of petrol. How many litres of petrol is needed to travel 675km?

 

See also

PROFIT AND LOSS

PROBLEM ON MULTIPLICATION OF MONEY

Money

ESTIMATION

HIGHEST COMMON FACTOR (HCF)