Percentages

Percentage is a way of expressing a number as a fraction of 100 (per cent means per hundred). It is denoted using the percent sign, %.
Example:
What is 200% of 30?

Answer: 200% × 30 = (200 / 100) × 30 = 60.

What is 13% of 98?

Answer: 13% × 98 = (13 / 100) × 98 = 12.74.

60% of all university students are male. There are 2400 male students. How many students are in the

 university?

Answer: 2400 = 60% × X, therefore X = (2400 / (60 / 100)) = 4000.

There are 300 cats in the village, and 75 of them are black. What is the percentage of black cats in that village?

Answer: 75 = X% × 300 = (X / 100) × 300, so X = (75 / 300) × 100 = 25, and therefore X% = 25%.

The number of students at the university increased to 4620, compared to last year's 4125, an absolute increase of 495 students. What is the percentual increase?
Answer: 495 = X% × 4125 = (X / 100) × 4125, so X = (495 / 4125) × 100 = 12, and therefore X% = 12%

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