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

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.