# Basic Maths

Basic maths for AQA AS Critical Thinking unit 2

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## Percentages

To calculate a percentage the formula is the given amount divided by the total amount multiplied by 100. For example if 48 out of 50 people owned a laptop the percentage of peope who owned a laptop would be 96%

If were given the information that 30% of people out of a total of 40 people supported animal testing the formula you would use is the total number of people multiplied by the percentage divided by 100. So it would be 40 multiplied by 0.30 so the answer would be 12.

To calculate percentage change you use the formula actual change divided by original value multiplied by 100. So if for example a car increases in value from £1000 to £1350 the percentage rise would be 350 divided by 1000 multiplied by 100 so the answer would be 35%.

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## Averages

There are 3 types of averages:

• The mean average. To work out the average you add up all the numbers and then divide it by how many numbers you add up. e.g. the  mean average of 1,3,3,5,7 is 3.8.
• The median average. The median average is the middle number when the numbers are in ascending order. e.g. the median average of 1,3,3,5,7 is 3.
• The mode average. The mode average is the number which appears the most times. e.g. the mode average of 1,3,3,5,7 is 3.
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