PERCENTAGE

In diagram A, the whole square has been divided into 100 small squares.In diagram B, the fraction of the small squares that are shaded is 35/100 or 7/20. Out of the 100 small squares, 35 are shaded. This is 35% of the whole square. We write 35% for 35 per cent.Percentage is related to fractions and decimals. Study the table below.
 

 

Fraction	Decimal	Percentage		Fraction	Decimal	Percentage
1/2	0.5	50%		9/10	0.9	90%
1/4	0.25	25%		1/8	0.125	12 ½%
3/4	0.75	75%		3/8	0.375	37 ½%
1/5	0.2	20%		5/8	0.625	62 ½%
2/5	0.4	40%		7/8	0.875	87 ½%
3/5	0.6	60%		1/20	0.05	5%
4/5	0.8	80%		1/25	0.04	4%
1/10	0.1	10%		1/50	0.02	2%
3/10	0.3	30%		1/100	0.01	1%
7/10	0.7	70%

 Expressing Parts of a Whole as Fractions, Decimals and Percentages

Examples:

1. Express 3/8 as a percentage.

3/8 x 100% = 300
                        8
= 37 1/2%

 

2. Express 0.45 as a percentage.

0.45 x 100% = 45%

3. Express 65% as a fraction.

65   = 13
100     20

4. Express 59% as a decimal.

59    = 59%
100

Expressing One Quantity as a Percentage of Another

Examples:

1. Express 20 cents as a percentage of $1.

  20    x 100% = 20%
100
20 cents is 20% of $1.

2. Express 250 g as a percentage of 2 kg.

250   x 100% = 12 ½%
2000

250 g is 12 1/2% of 2 kg.
 
 3. Express 425 m as a percentage of 1 km.

425     x 100% = 42 1/2 %
1000

425 m is 42% of 1 km.

Problems on Percentage

Examples:

1. Mrs Huang had $340. She spent 65% of it on clothes. How much money had she left?
 
 
Percentage of remaining sum = 100% - 65%
= 35%

Amount of money left = 35   x $340
                                    100
= $119

Mrs Huang had $119 left.

2. Mr Lin bought a camera for $189 at a discount of 16%. What was the usual price of the camera?
 

100% - 16% = 84%

84% of the usual price = $189

1% of the usual price = $189 / 84
= $189
     84

100% of the usual price = 100 x $189
                                                    84
= $225

The usual price of the camera was $225.