# Percentage

## Working with percentages - parts of a whole

Percentage can be calculated as

p = 100% P / W                             (1)

where

p = percentage (%)

P = part

W = whole

### Example - Contractors Materials

A contractor spent an amount of 100000 for materials in a custom home project. The total cost of the project was 200000. The materials percentage cost can be calculated as

p = 100% (100000) / (200000)

= 50%

### Example - Weight of Engine

Weight of an engine is 200 kg. The total weight of the car is 1500 kg. The percentage weight of the engine can be calculated as

p = 100% (200 kg) / (1500 kg)

= 13.3%

### Example - Increasing Price

The cost of a contract increase from 100000 to 120000. The percentage increase of the contract price can be calculated as

p = 100% (120000 - 100000) / (100000)

= 20%

### Example - Decreasing Price

The cost of a contract decrease from 100000 to 80000. The percentage decrease of the contract price can be calculated as

p = 100% (100000 - 80000) / (100000)

= 20%

## Related Topics

• Economics - Engineering economics - cash flow diagrams, present value, discount rates, internal rates of return - IRR, income taxes, inflation
• Mathematics - Mathematical rules and laws - numbers, areas, volumes, exponents, trigonometric functions and more

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